Linear programming decoding: The ultimate decoding technique for low density parity check codes

Linear programming (LP) decoding is an alternative to iterative algorithms for decoding low density parity check (LDPC) codes. Although the practical performance of LP decoding is comparable to message-passing decoding, a significant advantage is its relative amenability to nonasymptotic analysis. Moreover, there turn out to be a number of important theoretical connections between the LP decoding and standard forms of iterative decoding. These connections allow theoretical insight from the LP decoding perspective to be transferred to iterative decoding algorithms. These advantages encouraged many researchers to work in this recent decoding technique for LDPC codes. In this paper, LP decoding for LDPC code is extensively reviewed and is discussed in different segmented areas.     

Synthesis and functional evaluation of DNA-assembled polyamidoamine dendrimer clusters for cancer cell-specific targeting

We sought to produce dendrimers conjugated to different biofunctional moieties (fluorescein [FITC] and folic acid [FA]), and then link them together using complementary DNA oligonucleotides to produce clustered molecules that target cancer cells that overexpress the high-affinity folate receptor. Amine-terminated, generation 5 polyamidoamine (G5 PAMAM) dendrimers are first partially acetylated and then conjugated with FITC or FA, followed by the covalent attachment of complementary, 5'-phosphate-modified 34-base-long oligonucleotides. Hybridization of these oligonucleotide conjugates led to the self-assembly of the FITC- and FA-conjugated dendrimers. In vitro studies of the DNA-linked dendrimer clusters indicated specific binding to KB cells expressing the folate receptor. Confocal microscopy also showed the internalization of the dendrimer cluster. These results demonstrate the ability to design and produce supramolecular arrays of dendrimers using oligonucleotide bridges. This will also allow for further development of DNA-linked dendrimer clusters as imaging agents and therapeutics.     

Assessment of natural radioactivity in rice and their associated population dose estimation

ABSTRACT

The concentration of natural radioactivity in rice is an important parameter for the determination of population exposure by the ingestion of natural radionuclides during habitual consumption of food. All types of food including rice contain a detectable amount of natural radioactivity which successively relocate into the human body via the ingestion pathway. Rice is the main cultivated crop in Bangladesh and most of the Bangladeshi people consume rice as their staple food. Hence, studies on the evaluation of natural radioactivity in rice have been performed by gamma-ray spectrometry using High Purity Germanium (HPGe) detector in order to estimate various radiation hazards due to rice consumption. The average activity levels of natural radionuclides ²²⁶Ra, ²²⁸Ra and ⁴⁰K in the rice samples were 1.09?±?0.31, 0.17?±?0.21 and 4.70?±?1.59?Bq?kg^?1, respectively. The estimated effective doses for the respective radionuclides caused by the rice consumption were 43.69, 16.39 and 4.15?µSv?y^?1, respectively which was below the UNSCEAR compiled value. The calculated excess lifetime cancer risk (ELCR) values via rice consumption were found below the acceptable limit of 0.29?×?10^?3 for radiological risk.     

Feature extraction and damage-precursors for prognostication of lead-free electronics

Damage pre-cursors based health management and prognostication methodology has been presented for electronic systems in harsh environments. The framework has been developed based on a development of correlation between damage pre-cursors and underlying degradation mechanisms in lead-free packaging architectures. The proposed methodology eliminates the need for knowledge of prior stress histories and enables interrogation of system state using the identified damage pre-cursors.Test vehicle includes various area-array packaging architectures subjected to single thermo-mechanical stresses including thermal cycling in the range of −40 °C to 125 °C and isothermal aging at 125 °C. Experimental data on damage pre-cursors has been presented for packaging architectures encompassing flex-substrate ball grid arrays, chip-array ball grid arrays, and plastic ball grid arrays. Examples of damage proxies include phase-growth parameter, intermetallic thickness and interfacial stress variations. Damage proxies have been correlated with residual life. The damage proxies have also been correlated with computational finite-element model predictions. Plastic and creep strain energy densities have been correlated to the identified damage proxies.     

Nickel(II) chloride as an efficient and useful catalyst for chemoselective thioacetalization of aldehydes

A wide variety of acyclic and cyclic dithioacetals can be prepared chemoselectively from the corresponding aldehydes by employing a catalytic amount of nickel(II) chloride in dry CH₂Cl₂-MeOH (5:1) at room temperature in good yields. Some of the major advantages of this procedure are high chemoselectivity, ease of operation, high yields and also compatibility with other protecting groups.     

10 Tera Hertz Operation in One-Dimensional Quantum Interference Transistor (1-D QUIT) Devices

A high performance quantum interference transistor (QUIT) realized using high mobility 1-D MODFET channels is presented. The operation of this 1-D QUIT is based on electrostatic Aharonov-Bohm quantum interference effect. The channel length of the device is smaller than the inelastic coherence length of the electrons in the quantum well wire channel, otherwise scattering will randomize electron's phase and destroy the quantum interference effect. Transport characteristics of the 0.2 μm channel 1-D QUIT are calculated at 4.2 °K and compared with a two-dimensional QUIT device reported in literature. Our calculations show a significant improvement of the transconductance in one-dimensional transistors compared with its two-dimensional counterpart. The maximum frequency of operation of the 1-D QUIT is in the Tera Hertz regime, which makes it very attractive device for high frequency applications.     

Technical Note: Reduction of rational integrals related to linear and convex quadrilateral finite elements

We reduce a rational function of bivariate nth degree polynomial numerator with a linear denominator to a simple bivariate polynomial of degree (n ? 1) and a rational function of a single variate nth degree polynomial numerator with the same bivariate linear denominator. This has very greatly contributed to the evaluation of (n + 1)(n + 2)/2 rational integrals in bivariates to mere (n + 1) rational integral of a single variate and an integration of simple polynomial in bivariates. Thus the effort of integration is reduced several times and leads to simple analytical expressions in terms of the nodal coordinates. In order to illustrate the numerical process two examples are considered. © 2002 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 18: 759–770, 2002; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/num.10026.     

Phase-agile branch-line couplers using metamaterial lines

Two branch-line couplers are introduced that utilize a combination of regular microstrip (MS) and negative-refractive-index (NRI) lines. Interesting phase compensation (0/spl deg/ phase shift) at the output port and a choice of /spl plusmn/90/spl deg/ phase shift at the through port, with respect to the input, are possible. On the other hand, one of the dimensions of the coupler is significantly reduced, compared to a corresponding conventional branch-line coupler, but without any bandwidth degradation.     

Performance comparison of wavelength shift keying WDM system and conventional on-off WDM system in presence of four-wave mixing

Performance of wavelength shift keying (WSK) wavelength division multiplexed (WDM) system is analyzed and compared to that of conventional on-off keying (OOK) WDM system in respect of four-wave mixing (FWM) effect. WSK technique employs symmetric wavelength assignment and balanced detection to cancel FWM interference to first order. WSK–WDM outperforms conventional OOK–WDM at all signal levels and permits higher allowable input power, lower power penalty and higher transmission distance for a given bit-error rate of 10⁻⁹. WSK–WDM is also found to be noise resistant.     

Comparative study of the dissolution kinetics of electrolytic Ni and electroless Ni–P by the molten Sn3.5Ag0.5Cu solder alloy

Lead-free solders have high Sn content and high melting temperature, which often cause excessive interfacial reactions at the interface. Sn3.5Ag0.5Cu lead-free solder alloy has been used to identify its interfacial reactions with two-metal layer flexible substrates. In this paper we investigate the dissolution kinetics of Sn3.5Ag0.5Cu solder on electrolytic Ni/electroless NiP layer. It is found that during 1 min of reflow electroless NiP layer dissolves slightly lower than the electrolytic Ni due to the barrier layer formation between the intermetallic compounds (IMCs) and electroless NiP layer. Faster nucleation of IMCs on the electrolytic Ni layer is proposed as the main reason for higher initial dissolution. The appearance of P-rich Ni layer acts as a diffusion barrier layer between the solder and electroless NiP layer, which decreases the dissolution rate and IMCs growth rate than that of the electrolytic Ni layer, but weaken the interface and reduces the ball shear strength and reliability. After acquiring certain thickness P-rich Ni layer breaks and increases the diffusion rate of Sn and as a consequence both the IMCs growth rate and dissolution rate also increases. It is found that 3 μm thick electroless NiP layer cannot protect the Cu layer for more than 120 min at 250 °C. In electrolytic Ni shear strength does not change significantly and lower dissolution rate and more protective for Cu layer during long time molten reaction.