35,218 research outputs found
Physical layer DVB-SH performance prediction based on mutual information
Full text linkDigital Video Broadcasting-Satellite Handled (DVB-SH) is a hybrid satellite terrestrial broadcasting standard dedicated to provide video or audio services for handheld terminals. On the satellite part, this standard can make use of interleaving mechanisms to mitigate the effects of the Land Mobile Satellite channel. As a result, these mechanisms enable the in-time distribution of a codeword over a duration ranging from 100 ms to about 30 s, depending on their parameters. This mechanism significantly improves the error recovery performance of the code; however in the literature, a theoretical evaluation at system level of this improvement is missing. Moreover, carrying out Monte-Carlo simulations implementing real decoding processes on significant traveled distances is time prohibitive.
We propose hereafter a prediction method compatible with fast simulations to quantitatively evaluate the system performance in terms of Rate, Erroneous Second Ratio, and zapping time. This method is based on the computation of the mutual information between emitted and received symbols for QPSK modulation and turbo coding.
We demonstrate that our method reaches a prediction precision of the order of 0.1 dB, which is significantly better than two classical prediction methods. Moreover, our solution reduces the simulation time by a factor of 500 compared with Monte-Carlo. Beyond DVB-SH application, the presented approach can be applied in a large panel of satellite mobile systems and is completely new for the satellite community
Generic approach for hierarchical modulation performance analysis: application to DVB-SH
Full text linkBroadcasting systems have to deal with channel diversity in order to offer the best rate to the users. Hierarchical
modulation is a practical solution to provide several rates in function of the channel quality. Unfortunately the performance evaluation of such modulations requires time consuming simulations. We propose in this paper a novel approach based on the channel capacity to avoid these simulations. The method allows to study the performance in terms of spectrum efficiency of hierarchical and also classical modulations combined with error correcting codes. Our method will be applied to the DVB-SH standard which considers hierarchical modulation as an optional feature
FGF-2 facilitates binding of SH3 domain of PLC-gamma 1 to vinculin and SH2 domains to FGF receptor in corneal endothelial cells
No full textPURPOSE: To determine the cellular localization of the Src homology (SH)2 and SH3 domains of PLC-gamma 1 and their cytoplasmic binding partners, living corneal endothelial cells were microinjected with the fusion proteins containing SH domains. METHODS: Fusion proteins were prepared from plasmid vectors, and the fusion proteins containing SH2-SH2 [(SH2)2], SH2-SH2-SH3 [(SH2)2-SH3] or SH3 were isolated using affinity chromatography. Following microinjection, immunolocalization was analyzed using confocal laser microscope. RESULTS: Microinjected SH domains were targeted to the subcellular location following stimulation with FGF-2: the SH3 domain appeared to be targeted to cytoskeleton; the (SH2)2 domain showed a dual localization in cytoplasm and plasma membrane; the (SH2)2-SH3 domain was predominantly localized at membrane and perinuclear sites. In the absence of stimulation by FGF-2, the microinjected fusion proteins remained at the injection sites. When cytoplasmic binding partners were determined by double-staining, the SH3 domain demonstrated colocalization with vinculin: the staining profile of the SH3 domain was identical to that of vinculin, which demonstrates characteristic punctated profiles. The punctated staining of SH3 disappears toward the basal membrane, while that of vinculin remains in all confocal optical sections. On the other hand, some fraction of the (SH2)2 domain was colocalized with FGF receptor at the membrane site. When PLC-gamma 1 and F-actin were double-stained, the endogenous PLC-gamma 1 demonstrated a diffuse cytoplasmic staining and/or perinuclear staining, while phalloidin staining demonstrated that all cells have filamentous cytoplasmic distribution of F-actin. CONCLUSIONS: These findings indicate that the SH3 domain directs PLC-gamma 1 to bind to vinculin and that the SH2 domains may mediate the binding of PLC-gamma 1 to receptor tyrosine kinase. Furthermore, they suggest that phosphorylation is not required for targeting of PLC-gamma 1 to membrane or cytoskeleton sites.X114sciescopu
Prediction of performance of the DVB-SH system relying on mutual information
Full text linkDVB-SH (Digital Video Broadcasting-Satellite Handled) is a broadcasting standard dedicated to hybrid broadcasting systems combining a satellite and a terrestrial part. On the satellite part, dedicated interleaving and time slicing mechanisms are proposed to mitigate the effects of Land Mobile Satellite (LMS) channel, based on a convolutional interleaver. Depending on the parameters of this interleaver, this mechanism enables to split in time a codeword on duration from 100 ms to about 30s. This mechanism signi?cantly improves the error recovery performance of the code but in literature, exact evaluation at system level of this improvement is missing. The objective of this paper is to propose a prediction method compatible with fast simulations, to quantitatively evaluate the system performance in terms of Packet Error Rate (PER). The main dif?culty is to evaluate the decoding probability of a codeword submitted to several levels of attenuation. The method we propose consists in using as metric the Mutual Information (MI) between coded bit at the emitter side and the received symbol. It is shown that, by averaging the MI over the codeword and by using the decoding performance function g such that PER=g(MI)determined on the Gaussian channel, we can signi?cantly improve the precision of the prediction compared to the two other methods based on SNR and Bit Error Rate (BER). We evaluated these methods on three arti?cial channels where each codeword is transmitted with three or four different levels of attenuations. The prediction error of the SNR-based (resp. the input BER-based) method varies from 0.5 to 1.7 dB (resp. from 0.7 to 1.2 dB) instead of the MI-based method achieves a precision in the order of 0.1 dB in the three cases. We then evaluate this method on real LMS channels with various DVB-SH interleavers and show that the instantaneous PER can also be predicted with high accuracy
Temperature-sensitive pluronic/poly(ethylenimine) nanocapsules for thermally triggered disruption of intracellular endosomal compartment
No full textPluronic hydrogel nanoparticles cross-linked with poly(ethylenimine) (PEI) were synthesized by a modified emulsification/solvent evaporation method. Pluronic F-127 preactivated at the terminal group with p-nitrophenyl chloroformate was dissolved in dichloromethane, and the organic solution was emulsified in deionized water containing PEI by sonication. Primary amine groups of PEI in the aqueous phase were conjugated and/or crosslinked with activated Pluronic F-127 in the vicinity of the water/dichloromethane interface, resulting in the formation of shell-cross-linked Pluronic/PEI nanocapsules. Pluronic/PEI nanocapsules exhibited a volume transition behavior over a temperature range of 24-33 degrees C. The thermally reversible swelling/deswelling of Pluronic/PEI nanocapsules was caused by temperature-dependent hydrophobic interaction of cross-linked and/or grafted Pluronic polymer chains in the nanocapsules. Pluronic/PEI nanocapsules were utilized to break up intracellular endosomal compartments by swelling-induced destabilization of the endosomal membrane triggered by a cold-shock treatment.the Ministry of Health and
Welfare, Korea
Molecular-dynamics study of incoherent quasielastic neutron-scattering spectra of supercooled water RID F-2194-2011
No full textA molecular-dynamics simulation of extended simple point charge water in a time interval of 1 fs to 50 ns has been performed to study the single-particle dynamics of water at supercooled temperatures, In spite of the fact that upon supercooling water progressively evolves into a more open structure locally, the single-particle dynamics is nevertheless shown to be dominated by the so-called cage effect experienced by the test particle, The slow structural relaxation of the cage at low temperatures leads to the phenomenon of slow dynamics that can only be completely studied by following the trajectories into the nanosecond range. The objective df this paper is twofold. First, we test the accuracy of various approximations used in-previous analyses of. spectra from incoherent quasielastic neutron-scattering experiments. Second, we explore the possibility of an alternative method of analysis of high-resolution quasielastic neutron-scattering spectra, taking into account the slow dynamics in supercooled water. The approximations tested are the decoupling of the self-intermediate scattering function into a product of rotational and translational components, the physical interpretation of the origin of the experimentally;observed Debye Waller factor, the rotational-diffusion approximation of the rotational; intermediate scattering function, and the random jump diffusion approximation of the translational intermediate scattering function; Various approximations used previously for the component intermediate scattering functions are not sufficiently accurate. The reason for this is that at supercooled temperatures, due to the dominant cage: effect, the conventional picture of the stochastic single-particle diffusion loses its validity. The diffusion process is then progressively controlled by the structural relaxation of the cage
Single particle dynamics of supercooled water and the kinetic glass transition RID F-2194-2011
No full textA molecular dynamics simulation in a time interval of 1 fs to 50 ns has been performed to study the single-particle dynamics of supercooled SPC/E water. In spite of the fact that, upon supercooling, SPC/E water progressively evolves into a more open structure locally, the single particle dynamics is shown to be dominated by the so called cage effect. The structural relaxation of the cage at low temperatures leads to the phenomenon of slow dynamics that can only be completely studied by following the trajectories into the ns range. Such results can be interpreted in the framework of the mode-coupling theory for supercooled liquids. The so-called critical Angell temperature of supercooled water can thus be interpreted as kinetic glass transition temperature. For this simulation various approximation previously used in literature for the evaluation of the intermediate scattering function from the experimental results are no longer valid. In fact upon supercooling the stochastic single-particle diffusion looses its validity and the diffusion process is then progressively controlled by the structural relaxation of the cage. The possibility of an experimental test of such a behaviour on real supercooled water is explored
Model for single-particle dynamics in supercooled water RID F-2194-2011
No full textWe analyze a set of 10 M-step molecular dynamics (MD) data of low-temperature SPC/E model water with a phenomenological analytical model. The motivation is twofold: to extract various k-dependent physical parameters associated with the single-particle or the self-intermediate scattering functions (SISFs) of water at a deeply supercooled temperature and to apply this analytical model to analyse of new high resolution quasielastic neutron scattering data presented elsewhere. The SISF of the center of mass computed from the MD data show clearly time-separated two-step relaxations with a well defined plateau in between. We model the short time relaxation of the test particle as a particle trapped in a harmonical potential well with the vibrational frequency distribution function having a two-peak structure known from previous inelastic neutron scattering experiments. For the long time part of the relaxation, we take the alpha relaxation suggested by mode-coupling theory. The model fits the low-temperature SISK over the entire time range from 1 fs to 10 ns, allowing us to extract peak positions of the vibrational density of states, the structural relaxation rats 1/tau of the cage (the potential well) and the stretch exponent beta. The structural relaxation rate has a power law dependence on the magnitude of the wave vector transfer k and the stretch exponent varies from 0.55 at large k to unity at small k
Wellesly Sh. W. to Mr. James Meredith (2 October 1962)
Full text linkSigned by Wellesly Sh. W.https://egrove.olemiss.edu/mercorr_pro/1531/thumbnail.jp
Cerceris deserticola F. Morawitz 1890
No full textCerceris deserticola F. Morawitz, 1890 DISTRIBUTION IN IRAN. Fars (Atbaei et al., 2015).Published as part of Sadeghi, M., Fallahzadeh, M., Ostovan, H., Ljubomirov, T. & Hesami, Sh., 2019, Revised checklist of the genus Cerceris (Hymenoptera: Crabronidae) of Iran, with two new records, pp. 14-22 in Far Eastern Entomologist 395 on page 16, DOI: 10.25221/fee.395.3, http://zenodo.org/record/716487
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