Surface Chemistry of Vitamin: Pyridoxal 5′‐Phosphate (Vitamin B6) as a Multifunctional Compound for Surface Functionalization

Vitamins are non‐toxic compounds that perform a variety of biological functions and also available in a large quantity. Other than the usage as food supplements, few attempts have been made to use them as functional materials. In this study, we report that vitamin B6, pyridoxal 5′‐phosphate (PLP), is a multi‐functional molecule for oxide surface chemistry. PLP‐immobilized surfaces exhibit superhydrophilicity and even hemophilicity, enhancing proliferation, migration, and differentiation of mammalian cells. Unlike existing molecules used so far in surface modification, PLP has an intrinsic chemical reactivity toward biomacromolecules due to the presence of the aldehyde group. In fact, RGD peptide is covalently tethered onto PLP surfaces directly in one step without any chemical activation. Furthermore, PLP‐functionalized implant device showed rapid bone healing. As vitamin B6 is a FDA approved molecule for human usage, the surface chemistry of vitamin B6 potentially allows a fast route for surface functionalized medical devices into clinic.     

High-Speed Downlink Access in 3G Systems: A Portent for the Evolution of 4G Systems?

Due to the need of operators to protect the high levels of investment inthird generation (3G) wireless systems, it seems likely that the path tofourth generation (4G) wireless systems will be evolutionary rather thanrevolutionary. Currently there are a number of proposals beforestandardisation bodies such as 3GPP and 3GPP2 for extending the relevant3G systems to handle asymmetrical, packet-orientatedservices with very high downlink capacities. These proposals, whichinclude HDR and 1XTREME, may pave the way towards 4G systems.This paper outlines some of the salient features of HDR and 1XTREME:adaptive modulation, advanced hybrid ARQ, new fast access controlschemes, etc. On the basis of the trends inherent in theseproposals, some possible directions for the development of 4G systems arediscussed.     

LTE uplink MIMO receiver with low complexity interference cancellation

In LTE/LTE-A uplink receiver, frequency domain equalizers (FDE) are adopted to achieve good performance. However, in multi-tap channels, the residual inter-symbol and inter-antenna interference still exist after FDE and degrade the performance. Conventional interference cancellation schemes can minimize this interference by using frequency domain interference cancellation. However, those schemes have high complexity and large feedback latency, especially when adopting a large number of iterations. These result in low throughput and require a large amount of resource in software defined radio implementation. In this paper, we propose a novel low complexity interference cancellation scheme to minimize the residual interference in LTE/LTE-A uplink. Our proposed scheme can bring about 2 dB gains in different channels, but only adds up to 7.2 % complexity to the receiver. The scheme is further implemented on Xilinx FPGA. Compared to other conventional interference cancellation schemes, our scheme has less complexity, less data to store, and shorter feedback latency.     

Transformation champ proche — champ lointain bidimensionnelle et monodimensionnelle appliquée à des mesures de SER

In high frequency thercs measurement of large target must be done at important distances, so the distance of measurement (Fraunhofer’s distance) R is given by R ≥ 2d² /λ where d is the tranversal length of the target and λ the radiation wavelength. In this paper we present a method for target that are large relative to the curvature of the spherical wavefront and the curvature of the cylindrical wavefront. A two-dimensional analytical algorithm transforms the spherical wave (near-field) measurement into the desired plane wave (far-field) and a one-dimensionnal analytical algorithm transforms the cylindrical wave (near-field) measurement into the desired plane wave (far-field). We present some results on simulations and measurements. A comparison of one-dimensional and two-dimensional methods demonstrates the efficiency of the two dimensional methods.     

Value‐centric framework and pareto optimality for design and acquisition of communication satellites

Investments in space systems are substantial, indivisible, and irreversible, characteristics of high‐risk investments. Traditional approaches to system design, acquisition, and risk mitigation are derived from a cost‐centric mindset, and as such they incorporate little information about the value of the spacecraft to its stakeholders. These traditional approaches are appropriate in stable environments. However, the current technical and economic conditions are distinctly uncertain and rapidly changing. Consequently, these traditional approaches have to be revisited and adapted to the current context. We propose that in uncertain environments, decision‐making with respect to design and acquisition choices should be value‐based. We develop a value‐centric framework, analytical tools, and an illustrative numerical example for communication satellites. Our two proposed metrics for decision‐making are the system's expected value and value uncertainty. Expected value is calculated as the expected NPV of the satellite. The cash inflow is calculated as a function of the satellite loading, its transponder pricing, and market demand. The cash outflows are the various costs for owning and operating the satellite. Value uncertainty emerges due to uncertainties in the various cash flow streams, in particular because of market conditions. We propagate market uncertainty through Monte Carlo simulation, and translate it into value uncertainty for the satellite. The end result is a portfolio of Pareto‐optimal satellite design alternatives. By using value and value uncertainty as decision metrics in the down‐selection process, decision‐makers draw on more information about the system in its environment, and in making value‐based design and acquisition choices, they ultimately make more informed and better choices. Copyright © 2009 John Wiley & Sons, Ltd.     

The Impact of Political Talk Radio Exposure on Attributions About the Outcome of the 1996 U.S. Presidential Election

This study investigates the media's potential to affect audiences' interpretations of news events. It compares perceptions of the causes of the 1996 presidential election outcome across four media consumption groups: listeners to the program of Rush Limbaugh, listeners to other political talk radio, consumers of mainstream news media, and nonconsumers of news media. Limbaugh listeners were more likely to discount substantive election explanations than were consumers of other types of political talk radio, consumers of mainstream news media, and nonconsumers of news media. These differences in interpretation parallel differences between the content of his program and that of other media.     

Performance Limit of Chaotic Digital Waveform Communication Systems: Approach of Maximizing a Posteriori Probability

In this paper, we investigate a bandpass chaotic waveform communication system in an additive white Gaussian noise channel environment. By making use of the signalspace diagram and maximizing the a posteriori probability, we derive the conditions under which the optimum bit error performance can be achieved. In particular, we make use of a binary communication system to illustrate how the modulator and demodulator should be constructed in order to achieve the best error performance. Finally, the noise performance bound is determined for chaotic digital waveform communications.     

Location Estimation via Support Vector Regression

Location estimation using the global system for mobile communication (GSM) is an emerging application that infers the location of the mobile receiver from multiple signals measurements. While geometrical and signal propagation models have been deployed to tackle this estimation problem, the terrain factors and power fluctuations have confined the accuracy of such estimation. Using support vector regression, we investigate the missing value location estimation problem by providing theoretical and empirical analysis on existing and novel kernels. A novel synthetic experiment is designed to compare the performances of different location estimation approaches. The proposed support vector regression approach shows promising performances, especially in terrains with local variations in environmental factors     

Comparative study of gigahertz CMOS LC quadrature voltage-controlled oscillators with relevance to phase noise

This review paper presents a comparative study of published integrated submicron CMOS quadrature voltage-controlled oscillator designs, based on LC resonator tanks operating at gigahertz frequencies. Although special reference to phase noise reduction is made, the comparison also concerns issues such as power consumption, tuning range and the phase accuracy of the quadrature signals. The effect of supply voltage reduction on the choice of the oscillator topology is also included in the discussion.