Reference Carriers Research Articles

Корреляционная оценка при передаче дискретной информации на основе шумовых хаотических сигналов с временными окнами.

Wireless noise communication system based on the transmitted reference technique (TRT) is proposed for a covert data transmission through additive white Gaussian noise (AGWN) channel. Noise waveforms with the time windows are formed for data transmission using (3.1–4.1) GHz band-pass filters with symmetrical finite impulse response (FIR). FIR filter design includes the specification of the rectangular frequency response and the selection of appropriate window functions, which satisfy pass-band and attenuation specifications. Spread spectrum noise communications apply the time diversity between the noise reference and informative noise carriers delayed at the time interval T = 6 ns exceeding the noise coherent time τc = 1 ns. The delayed noise carriers are multiplied by antipodal binary symbols bl = ±1 at the same rate to informative data stream. The delivered noise reference is transmitted through wireless channel simultaneously with delayed noise waveforms contained informative components. Spectrum modulation of transmitted waveforms is performed by means of linear superposition between the noise reference and informative noise carriers delayed at time interval T. Spectral power density of result noise signals is modulated by antipodal harmonic functions with the period in inverse proportion to relative time delay Т. The coherent convolution of continuous noise signals is produced by the correlation receiver during every informative symbol interval. The correlation time delay in the receiver channel corresponds to the diversity time delay Т of informative noise signals. The correlation estimation problem appears in the case of data transmitting on the base of continuous noise carriers. Correlation estimations are statistical evaluated for total noise signals propagating throw AGWN channel. Intersystem jamming is excited at the output of correlation receiver even if noise informative carriers are transmitted over a wireless channel without thermal noise. Autocorrelation receiver output is randomly deviated near the average value according to informative data rate. Window method is proposed for a digital compensation of random distortions in correlation estimations. It is shown, that utilizing continuously noise signals with the time windows permits to decrease randomly fluctuations of correlation estimations.

Novel guanidinylated bioresponsive poly(amidoamine)s designed for short hairpin RNA delivery.

Two different disulfide (SS)-containing poly(amidoamine) (PAA) polymers were constructed using guanidino (Gua)-containing monomers (ie, arginine [Arg] and agmatine [Agm]) and N,N′-cystamine bisacrylamide (CBA) by Michael-addition polymerization. In order to characterize these two Gua-SS-PAA polymers and investigate their potentials as short hairpin RNA (shRNA)-delivery carriers, pSilencer 4.1-CMV FANCF shRNA was chosen as a model plasmid DNA to form complexes with these two polymers. The Gua-SS-PAAs and plasmid DNA complexes were determined with particle sizes less than 90 nm and positive ζ-potentials under 20 mV at nucleic acid:polymer weight ratios lower than 1:24. Bioresponsive release of plasmid DNA was observed from both newly constructed complexes. Significantly lower cytotoxicity was observed for both polymer complexes compared with polyethylenimine and Lipofectamine 2000, two widely used transfection reagents as reference carriers. Arg-CBA showed higher transfection efficiency and gene-silencing efficiency in MCF7 cells than Agm-CBA and the reference carriers. In addition, the cellular uptake of Arg-CBA in MCF7 cells was found to be higher and faster than Agm-CBA and the reference carriers. Similarly, plasmid DNA transport into the nucleus mediated by Arg-CBA was more than that by Agm-CBA and the reference carriers. The study suggested that guanidine and carboxyl introduced into Gua-SS-PAAs polymers resulted in a better nuclear localization effect, which played a key role in the observed enhancement of transfection efficiency and low cytotoxicity. Overall, two newly synthesized Gua-SS-PAAs polymers demonstrated great potential to be used as shRNA carriers for gene-therapy applications.

Interaction between interleukin-10 (IL-10) polymorphisms and dietary fibre in relation to risk of colorectal cancer in a Danish case-cohort study

BackgroundMore than 50% of the colorectal cancer (CRC) etiology has been attributed to diet. Established or suspected dietary factors modifying risk of CRC are red meat, cereals, fish, and fibre. Diet and lifestyle may be linked to cancer through inflammation. Interleukin-10 (IL-10) is an anti-inflammatory cytokine. We wanted to test if dietary factors and IL10 polymorphisms interact in relation to colorectal carcinogenesis.MethodsThe functional IL10 polymorphism C-592A (rs1800872) and the marker rs3024505 were assessed in relation to diet and lifestyle in a nested case-cohort study of 378 CRC cases and 775 randomly selected participants from a prospective study of 57,053 persons. Genotyping data on the IL10 polymorphism C-592A, smoking and non-steroidal anti-inflammatory drugs (NSAID) was retrieved from Vogel et al. (Mutat Res, 2007; 624:88). Incidence rate ratios (IRR) and 95% Confidence Interval (95% CI) were calculated.ResultsNo associations were found between the IL10 rs3024505 polymorphism and risk of CRC. There was interaction between rs3024505 and dietary fibre (P-value for interaction = 0.01). IL10 rs3024505 homozygous wildtype carriers were at 27% reduced risk of CRC per 10 g fibre per day (95% CI: 0.60-0.88) whereas variant carriers had no risk reduction by fibre intake. Also, interaction between IL10 C-592A and intake of fibre was found (P-value for interaction = 0.02). Among those eating <17.0 grams of fibre per day, carriers of an C-592A variant allele had a statistically significantly higher risk of colorectal cancer compared to homozygous wildtypes. No significant differences in colorectal cancer risk were observed between the reference group (CC and <17.0 g/day) and carriers of one C-592A variant allele eating 17.0 or more grams of dietary fibre per day. This suggests that the increased risk due to carrying the variant allele can be overcome by higher fibre intake. No interactions between IL10 polymorphisms and dietary meat, cereal, or fish intake, or between IL10 rs3024505 and smoking or NSAID use were found.ConclusionsIn this northern Caucasian cohort we found interaction between IL10 and dietary fibre in CRC carcinogenesis. High intake of fibre seems to protect against CRC among individuals with IL10 related genetic susceptibility to CRC. This finding should be evaluated in other prospective and population-based cohorts with different ethnic groups.

PMD tolerant direct-detection polarization division multiplexed OFDM systems with MIMO processing

This work proposes a novel direct-detection polarization division multiplexed OFDM scheme without the need of dynamic polarization control at a polarization-diverse receiver, and the proposed scheme is robust against polarization mode dispersion. Setting the frequency difference between two polarization-orthogonal reference carriers as one subcarrier spacing, possible signal fading can be avoided, and the corresponding interference from adjacent subcarriers is eliminated by a novel MIMO algorithm. The penalty caused by high channel matrix condition number can be decreased by inserting empty tones among subcarriers, and the polarization-dependent OSNR penalty at the BER of 10⁻³ is <3.6 dB with an empty tone inserted every 8 subcarriers. Moreover, the numerical results demonstrate the 16 × 10³-ps/nm chromatic dispersion and the 300-ps differential group delay will not induce additional penalty.

The Research of Collaborative Navigation Localization Based on GPS and INS Integrated System

The integrated navigation system with GPS/INS can obtain precision navigation accuracy. But the accuracy will reduce sharply with the outage of GPS signal for a long time. In this case, the collaborative navigation will play key role. The method of received signal strength (RSS) is to be proposed in this paper to solve the problem of distance measurement between the reference carriers and unknown carrier. Navigation error data were calculated and simulation analysis of the carrier comparison to the situation with collaborative supporting of reference carriers was processed. At the same time, the Matlab simulation to the carrier with INS was carried on. The analysis results of experimental data showed the navigation accuracy of the carrier with unstable GPS/INS signal being improved about 40 percents with the collaborative aids of the reference carriers. The analysis proved the effectiveness of the collaborative navigation method.

Characterization and hydrotreating performance of NiMo catalysts supported on nanostructured titanate

Abstract A nanostructured protonated titanate, synthesized by alkaline hydrothermal treatment of TiO2, has been investigated as a precursor support for NiMo hydrotreating catalyst and compared to alumina and titania as reference carriers. Each of the three powders was extrudated and calcined to obtain the properly shaped support, which was analyzed with respect to textural and acidity properties and then metal impregnated by insipient wetness method and sulfided at constant conditions to produce the final catalyst. The corresponding NiMo catalysts in the precursor oxide form were characterized by X-ray diffraction (XRD), thermogravimetry (TGA), transmission electron microscopy (TEM), temperature programmed reduction (TPR) and N2 adsorption, whereas the active sulfided form was thoroughly examined by TEM and tested as for their tetralin hydrogenation activity. The results indicated that in spite of the higher surface area of the precursor NiMo-catalyst supported on the nanostructured carrier, its layered nature and one-dimensional morphology was lost after sulfidation under H2S/H2 atmosphere at 300 °C. The dispersion of the sulfided active phase as examined by high resolution TEM was similar to that exhibited by the counterparts supported on alumina and nanocrystalline anatase, which was in agreement with the similar activities for tetralin hydrogenation found for the three tested catalysts. On the other hand, the titanate derived catalyst showed higher yields of ring opening of tetralin than the alumina supported catalyst, which was tentatively explained by the higher Bronsted acidity of the nanostructured support as measured by decomposition of adsorbed n-propylamine.

Differential UWB Communications With Digital Multicarrier Modulation

As a high-rate alternative of impulse radio (IR) ultrawideband (UWB) communications, analog and digital multicarrier UWB radios with coherent detection have been introduced. In this paper, we investigate digital multicarrier differential (MCD) modulation and demodulation schemes for UWB communications. In our approach, the differential encoding and decoding are carried out across multiple digital carriers in the frequency domain. Hence, channel estimation is bypassed by using neighboring carriers as reference carriers. Compared with the transmitted reference TR-UWB which relies on delaying and correlating the received signal segments in time domain, our MCD-UWB avoids the need for analog delay elements. In addition, our digital-carrier based approach does not incur any spectrum expansion. We also show that our approach enables variable data rates, and remains operational even in the presence of severe interframe interference (IFI). In addition, the small spacing between differentially encoded carriers ensures that the data rate is not limited by the channel coherence bandwidth. Furthermore, our schemes are flexible in providing variable-rate transmissions. Simulations are also carried out to corroborate our theoretical analysis.

Humidity Dependence of Tribocharging of Toner Surface Treated with Hydrophobic and Hydrophylic Silica

In this study, the effect of humidity on the tribocharging of toner surface treated with hydrophobic and hydrophilic silicas was compared. A normally positively charging toner was surface treated with either silica, and toner charge to mass was measured as a function of humidity and silica concentration using a set of reference carriers. The data were analyzed using an extension of the surface state model of tribocharging to assess the effect of humidity on toner work function, the density of states of charging sites, and toner surface conductivity. It was found that toner surface treated with either silica has a lower charge at high humidity. Analysis shows that both the work function and a combination of toner conductivity and the density of states of the charging sites change in the direction to decrease charge at high humidity. Therefore, even in the absence of increasing toner conductivity at high humidity, charge will be lower at high humidity for both silicas. Thus, the use of hydrophobic silica surface treatment does not reduce the sensitivity of toner charge to humidity.

Bacteriological validation of a new apparatus for disinfection of hospital waste at the point of disposal.

To evaluate the ability of a new apparatus (Dipsys 25, Société SGN, Bagnols sur Cèze, France) to disinfect biomedical waste, including both potentially infectious agents and the normal saprophytic flora of the waste. Disinfection was assessed using standard methods (reference strains were fixed on reference carriers according to the French AFNOR methods) and nonstandard assays. Assays in conditions of hospital use, evaluations of bacterial survival during storage, sporicidal effect, and spore survival during storage were performed in parallel. Finally, bactericidal effect in extreme conditions (association of high contamination and high bacterial protection conditions) was tested with normal fecal flora. Bacterial counts were performed after treatment by the apparatus and without treatment (controls). All tests were carried out in triplicate. In all treated carriers, a bacterial population decrease of at least 5 log10 was obtained. Assays performed in hospital-use conditions did not show any bacterial growth. Concerning the evaluation of sporicidal effect and spore revival during conservation, a minimum reduction of 5 log10 was observed in all assays performed, without survival. Finally, concerning assays in extreme conditions, the decrease of bacterial population was between 5 log10 and 10 log10 for vegetative anaerobes of normal fecal flora. Under our study conditions, the study apparatus reduced the tested microbial populations by a minimal factor of 5 log10. The main advantage of the apparatus is the opportunity to treat contaminated waste inside hospital wards, at the point of initial collection, without pulverization, by nonspecialized staff.

Surface State Analysis of Tribocharging Data for Several Toners using a Set of Reference Carriers

Surface state models of tribocharging have been successful in explaining many features of the charging of two-component electrophotographic developers. In this paper a new approach for constructing triboelectric series is presented based on surface state models. This method of analysis has several advantages: it requires only limited experimental data, allows the construction of triboelectric series, and makes it possible to separate the effects of the concentration of charging sites and differences in work function on charging. The method was used to analyze tribocharging data recently published by K.-Y. Law and co-workers. Both the work functions and charging site densities of toners treated with various silicas and ionic charge control agents are shown to depend on the surface composition of the toner. Surface treatment with silica causes the work function to increase, shifting the treated toner lower in the triboelectric series. The greater the surface area of the silica, the greater the shift. Hydrophobic silicas cause a greater shift than hydrophilic silicas. For toner surface treated with a set of negative charge control agents (3,5-di-tbutylsalicylic acid and its salts with Li, Na, K, and Rb) it was found that, with the exception of Cs and H, the binding energy of the ions decreases as the ions become heavier, while the concentration of charging sites increases. The results show that the high density of states limit does not apply to all of these materials.

Performance of a carrier-recovery loop in a satellite modem

The paper describes a carrier recovery loop for the coherent demodulation of a digital satellite modem for mobile systems. The loop is data aided, employing decision feedback. The modem transmits a band-limited differentially encoded quaternary phase-shift-keyed (DEQPSK) signal over a satellite link. Several different earth stations are assumed to have simultaneous access to a given transponder, in an arrangement of frequency-division multiple access (FDMA). Thus the DEQPSK signals that occupy the immediately adjacent frequency bands can introduce adjacentchannel interference (ACI) into the transmitted DEQPSK signal. The high-power amplifier (HPA) at the earth station transmitter introduces AM-AM and AM-PM conversion effects into the DEQPSK signal, but the satellite transponder is linear. A baseband predistorter operates on the baseband signals at the input to the modulator and assumes a prior knowledge of the HPA characteristics. A carrier-recovery loop is used at the receiver to generate the in-phase and quadrature reference carriers employed by the coherent demodulator. The performance of the system is studied by computer simulation, over a range of different conditions and with different arrangements of the modem, and the results are used to determine the preferred modem design.

Doppler‐shift correction by the DFT, for a QPSK satellite modem

AbstractThis paper describes a novel technique for the measurement and correction of the Doppler shift (frequency offset) in a received QPSK signal that has been transmitted over a satellite link. The satellite is here assumed to be in a non‐geostationary orbit, and correction of the Doppler shift is required to be achieved as soon as the satellite rises above the horizon, when the Doppler shift may be very high and the signal/noise ratio very low. The receiver now has no prior knowledge of the transmitted data, so that a non‐data‐aided system must be used, capable of operating under seriously adverse conditions.The selected technique measures the DFTs of successive blocks of samples of the received and demodulated signal, and from the DFTs it derives a control signal for the VCO, which generates the in‐phase and quadrature reference carriers for the coherent demodulator. The frequency of the latter is adjusted to reduce the residual Doppler shift in the demodulated signal to a sufficiently small value, so that correct phase synchronization of the VCO on to the received signal carrier can then be achieved by means of an appropriate conventional system (not considered here).The paper describes the new technique of Doppler shift correction, and presents the results of computer‐simulation tests to measure the time taken to correct an initial Doppler shift of 5 kHz in the received QPSK signal, at very low signal/noise ratios.

Doppler-shift correction via correlation for a received QPSK signal

The paper considers a novel technique for the measurement and correction of the Doppler shift (frequency offset) in a received QPSK signal, where the Doppler shift may be very high, the signal/noise ratio very low, and the receiver has no prior knowledge of the received data symbols. The technique is designed for synchronous data and is to operate prior to the instigation of a phase locking algorithm necessary for coherent demodulation. It reduces the Doppler shift to a value within the capture range of the phase correction loop, and does not operate during the phase acquisition period nor during data detection. The residual Doppler shift in the coherently demodulated baseband signal at the receiver is measured by correlating this signal with two components (complex exponentials) of equal frequency but one positive and the other negative, where the frequency is an appropriate fraction (typically around one half) of the highest frequency component of the baseband signal. Depending on which of the two correlators gives the greater output signal, the frequency of the reference carriers in the coherent demodulator is increased or decreased to reduce the residual Doppler shift in the demodulated baseband signal. The paper first describes various arrangements of the new Doppler-shift corrector, together with the original DFT Doppler-shift corrector, from which these have been derived, and it then presents the results of computer-simulation tests to assess the performances of the different systems.