Low-Complexity Near-MAP Decoding of Large Non-Orthogonal STBCs Using PDA

Non-orthogonal space-time block codes (STBC) from cyclic division algebras (CDA) are attractive because they can simultaneously achieve both high spectral efficiencies (same spectral efficiency as in V-BLAST for a given number of transmit antennas) as well as full transmit diversity. Decoding of non-orthogonal STBCs with hundreds of dimensions has been a challenge. In this paper, we present a probabilistic data association (PDA) based algorithm for decoding non-orthogonal STBCs with large dimensions. Our simulation results show that the proposed PDA-based algorithm achieves near SISO AWGN uncoded BER as well as near-capacity coded BER (within 5 dB of the theoretical capacity) for large non-orthogonal STBCs from CDA. We study the effect of spatial correlation on the BER, and show that the performance loss due to spatial correlation can be alleviated by providing more receive spatial dimensions. We report good BER performance when a training-based iterative decoding/channel estimation is used (instead of assuming perfect channel knowledge) in channels with large coherence times. A comparison of the performances of the PDA algorithm and the likelihood ascent search (LAS) algorithm (reported in our recent work) is also presented.

The Amenability Studies on Beneficiation of Low Grade Phyllite Deposits of Tungsten From Degana, Rajasthan

The phyllite deposit of Degana, Rajasthan, containing tungsten values in the form of wolframite, (Fe, MnWO sub 4 ) finely dispersed in the quartz groundmass, has been quantitatively analysed to give 0.063% WO sub 3 , 6.66% Fe sub 2 O sub 3 , 14.30% Al sub 2 O sub 3 and 67.4% SiO sub 2 . The major gangue minerals identified are quartz, iron oxides and mica along with minor amounts of graphite, fluorite and sulphides. The amenability of the ore to gravity concentration, magnetic separation and a combination of the processes has been studied. A combination of tabling on --100 mesh ground ore and dry magnetic separation of the tabled concentrate gave a final concentrate containing 1.834% WO sub 3 with an overall recovery of only 4.6%. The complex mineralogy combined with fine dispersion of very low W values have contributed to the low recoveries and grades. Graph, photomicrographs. 10 ref.--AA

Low-voltage varistors from ZnO+CaMnO3 ceramics

: Varistors prepared from ZnO with CaMnO3 perovskite as the only forming additive, exhibit voltage-limiting current-voltage characteristics with nonlinearity coefficient alpha up to 380 at low voltages of 1.8-12 V/mm. High nonlinearity is observed only with a suitable combination of processing parameters. The most crucial of them are (i) initial formulation of ceramics and (ii) the sintering temperature and conditions of post-sinter annealing. An electrically active intergranular phase is formed between ZnO grains with the composition ranging from Ca4Mn6Zn4O17 to Ca4Mn8Zn3O19, which creates the n-p-n heterojunctions. The low-voltage nonlinearity originates as a result of higher concentration of Mn(III)/Mn(IV) present at the grain boundary layer regions, being charge compensated by zinc vacancies. Under the external electric field, the barrier height is lowered due to the uphill diffusion of holes mediated by the acceptor states. Above the turn-on voltages, the unhindered transport of charge carriers between grains generates high current density associated with large nonlinearity.

A simple low-cost electrical switching analyzer for I-V characterization of switching samples and devices

The phenomena of nonlinear I-V behavior and electrical switching find extensive applications in power control, information storage, oscillators, etc. The study of I-V characteristics and switching parameters is necessary for the proper application of switching materials and devices. In the present work, a simple low-cost electrical switching analyzer has been developed for the measurement of the electrical characteristics of switching materials and devices. The system developed consists of a microcontroller-based excitation source and a high-speed data acquisition system. The design details of the excitation source, its interface with the high-speed data acquisition system and personal computer, and the details of the application software developed for automated measurements are described. Typical I-V characteristics and switching curves obtained with the system developed are also presented to illustrate the capability of the instrument developed.

A density matrix renormalization group study of low-lying excitations of polythiophene within a Pariser-Parr-Pople model

Symmetrized density-matrix-renormalization-group calculations have been carried out, within Pariser-Parr-Pople Hamiltonian, to explore the nature of the ground and low-lying excited states of long polythiophene oligomers. We have exploited C-2 symmetry and spin parity of the system to obtain excited states of experimental interest, and studied the lowest dipole allowed excited state and lowest dipole forbidden two photon state, for different oligomer sizes. In the long system limit, the dipole allowed excited state always lies below the lowest dipole forbidden two-photon state which implies, by Kasha rule, that polythiophene fluoresces strongly. The lowest triplet state lies below two-photon state as usual in conjugated polymers. We have doped the system with a hole and an electron and obtained the charge excitation gap and the binding energy of the 1(1)B(u)(-) exciton. We have calculated the charge density of the ground, one-photon and two-photon states for the longer system size of 10 thiophene rings to characterize these states. We have studied bond order in these states to get an idea about the equilibrium excited state geometry of the system. We have also studied the charge density distribution of the singly and doubly doped polarons for longer system size, and observe that polythiophenes do not support bipolarons.

A low-cost lead-acid battery with high specific-energy

Lightweight grids for lead-acid battery grids have been prepared from acrylonitrile. butadiene styrene (ABS) copolymer followed by coating with lead. Subsequently, the grids have been electrochemically coated with a conductive and corrosion-resistant layer of polyaniline. These grids are about 75% lighter than those employed in conventional lead-acid batteries. Commercial-grade 6V/3.5 Ah (C-20-rate) lead-acid batteries have been assembled and characterized employing positive and negative plates constituting these grids. The specific energy of such a lead-acid battery is about 50 Wh/kg. The batteries can withstand fast charge-discharge duty cycles.

Low-temperature polymer precursor-based synthesis of nanocrystalline particles of lanthanum calcium manganese oxide (La0.67Ca0.33MnO3) with enhanced ferromagnetic transition temperature

We report a simple modified polymeric precursor route for the synthesis of highly crystalline and homogenous nanoparticles of lanthanum calcium manganese oxide (LCMO). The LCMO phase formation was studied by thermal analysis, x-ray powder diffraction, and infrared spectroscopy at different stages of heating. These nanocrystallites (average particle size of 30 nm) possess ferromagnetic-paramagnetic transition temperature (T-c) of 300 K, nearly 50 K higher than that of a single crystal. The Rietveld analysis of the powder x-ray diffraction data of the nanopowders reveals significant lattice contraction and reduction in unit cell anisotropy-these structural changes are correlated to the enhancement in T-c.

Development of a low-cost portable colorimeter for the estimation of fluoride in drinking water

People in many countries are affected by fluorosis owing to the high levels of fluoride in drinking water. An inexpensive method for estimating the concentration of the fluoride ion in drinking water would be helpful in identifying safe sources of water and also in monitoring the performance of defluoridation techniques. For this purpose, a simple, inexpensive, and portable colorimeter has been developed in the present work. It is used in conjunction with the SPADNS method, which shows a color change in the visible region on addition of water containing fluoride to a reagent solution. Groundwater samples were collected from different parts of the state of Karnataka, India and analysed for fluoride. The results obtained using the colorimeter and the double beam spectrophotometer agreed fairly well. The costs of the colorimeter and of the chemicals required per test were about Rs. 250 (US$ 5) and Rs. 2.5 (US$ 0.05), respectively. In addition, the cost of the chemicals required for constructing the calibration curve was about Rs. 15 (US$ 0.3). (C) 2010 Elsevier B.V. All rights reserved.

An SIMD machine for low-level vision

This paper presents an SIMD machine which has been tuned to execute low-level vision algorithms employing the relaxation labeling paradigm. Novel features of the design include: 1. (1) a communication scheme capable of window accessing under a single instruction. 2. (2) flexible I/O instructions to load overlapped data segments; and 3. (3) data-conditional instructions which can be nested to an arbitrary degree. A time analysis of the stereo correspondence problem, as implemented on a simulated version of the machine using the probabilistic relaxation technique, shows a speed up of almost N2 for an N × N array of PEs.

A Low ML-Decoding Complexity, High Coding Gain, Full-Rate, Full-Diversity STBC for 4 x 2 MIMO System

This paper proposes a full-rate, full-diversity space-time block code(STBC) with low maximum likelihood (ML) decoding complexity and high coding gain for the 4 transmit antenna, 2 receive antenna (4 x 2) multiple-input multiple-output (MIMO) system that employs 4/16-QAM. For such a system, the best code known is the DjABBA code and recently, Biglieri, Hong and Viterbo have proposed another STBC (BHV code) for 4-QAM which has lower ML-decoding complexity than the DjABBA code but does not have full-diversity like the DjABBA code. The code proposed in this paper has the same ML-decoding complexity as the BHV code for any square M-QAM but has full-diversity for 4- and 16-QAM. Compared with the DjABBA code, the proposed code has lower ML-decoding complexity for square M-QAM constellation, higher coding gain for 4- and 16-QAM, and hence a better codeword error rate (CER) performance. Simulation results confirming this are presented.

Uniparental DNA markers and forensic genetics in Finland

Over the years, a wide range of methods to verify identity have been developed. Molecular markers have been used for identification since the 1920s, commencing with blood types and culminating with the advent of DNA techniques in the 1980s. Identification is required by authorities in many occasions, e.g. in disputed paternity cases, identification of deceased, or crime investigation. To clarify maternal and paternal lineages, uniparental DNA markers in mtDNA and Y-chromosome can be utilized. These markers have several advantages: male specific Y-chromosome can be used to identify a male from a mixture of male and female cells, e.g. in rape cases. MtDNA is durable and has a high copy number, allowing analyses even from old or degraded samples. However, both markers are lineage-specific, not individualizing, and susceptible to genetic drift. Prior to the application of any DNA marker in forensic casework, it is of utmost importance to investigate its qualities and peculiarities in the target population. Earlier studies on the Finnish population have shown reduced variation in the Y-chromosome, but in mtDNA results have been ambiguous. The obtained results confirmed the low diversity in Y-chromosome in Finland. Detailed population analysis revealed large regional differences, and extremely reduced diversity especially in East Finland. Analysis of the qualities affecting Y-chromosomal short tandem repeat (Y-STR) variation and mutation frequencies, and search of new polymorphic markers resulted a set of Y-STRs with especially high diversity in Finland. Contrary to Y-chromosome, neither reduced diversity nor regional differences were found in mtDNA within Finland. In fact, mtDNA diversity was found similar to other European populations. The revealed peculiarities in the uniparental markers are a legacy of the Finnish population history. The obtained results challenge the traditional explanation which emphasizes relatively recent founder effects creating the observed east-west patterns. Uniparentally inherited markers, both mtDNA and Y-chromosome, are applicable for identification purposes in Finland. By adjusting the analysed Y marker set to meet the characteristics of Finnish population, Y-chromosomal diversity increases and the regional differentiation decreases, resulting increase in discrimination power and thus usefulness of Y-chromosomal analysis in forensic casework.

EU Accession and FDI inflows : The cases of the Czech Republic and Slovakia

Central and East European countries have faced a difficult process of transition since the dissolution of the Soviet bloc. Ten transition countries (Hungary, Poland, teh Czech Republic, Slovakia, Slovenia, Lithuania, Latvia, Estonia, Bulgaria and Romania have chosen to join the EU and have moulded their transition reforms to ensure the compliance of their legal and institutional framework with EU requirements. The high levels of FDI attracted by the candidate countries for EU membership had been attributed to rapid transition of the countries aiming to join the European Union and the fact that favourable evaluations by EU authorities of the progress made by the candidates had a large impact on improving investor confidence. The aim of this paper is to investigate the reform strategies of the Czech Republic and Slovakia undertaken when the countries were preparing for EU membership and the dynamics of FDI inflows into these economies. Subsequently a comparative analysis of FDI stocks in these countries is conducted. We find that both countries faced similar economic challenges in implementing structural and institutional reforms. In accordance with EU requirements the Czech Republic and Slovakia have perfected their legal and institutional framework, increased the authority of regulatory and supervisory bodies and focused on implementation of new or amended legislation. During the period of the analysis (1998 - 2007) the Czech Republic and Slovakia have attracted increasing amounts of FDI. Comparative analysis in terms of important determinants of FDI reveals further similar features: macroeconomic stability; an open and liberalised market; low labour costs compared to EU-15 and a similar breakdown of FDI inflows by investor country. Consequently, the fact that the Czech Republic received much larger volumes of net FDI inflows could be attributed to the difference in market size between the two states. This conclusion is consistent with previous empirical studies that list market size among the main determinants of FDI. However, when we look at FDI as a percentage of GDP the evidence is more mixed. In 2004 - 2007, Slovakia has surpassed the Czech Republic twice. Whether this tendency will persist remains to be seen. The analysis in this paper based on empirical data. However, the choice of the method, namely case studies and comparative analysis, means that the conclusions of this study are theoretical and remain to be further tested in quantitative models.

Low-temperature synthesis of novel layered alkali metal-MoO3 bronzes and hexagonal bronzes of the type KyW1−xMoxO3

A new class of layered alkali metal-MoO3 bronzes,AxMoO3 (A =Li, Na, K, Rb), with nearly the same unit cell parameters as the host oxide has been synthesized by the solid-state reaction of MoO3 with alkali metal iodides around 575 K; LixMoO3 absorbs H2O causing an increase in theb parameter of the unit cell. Hexagonal potassium bronzes of W1−xMoxO3 are synthesized for the first time.

Molecular features of colorectal cancer predisposition and progression

Both inherited genetic variations and somatically acquired mutations drive cancer development. The aim of this thesis was to gain insight into the molecular mechanisms underlying colorectal cancer (CRC) predisposition and tumor progression. Whereas one-third of CRC may develop in the context of hereditary predisposition, the known highly penetrant syndromes only explain a small fraction of all cases. Genome-wide association studies have shown that ten common single nucleotide polymorphisms (SNPs) modestly predispose to CRC. Our population-based sample series of around thousand CRC cases and healthy controls was genotyped for these SNPs. Tumors of heterozygous patients were analyzed for allelic imbalance, in an attempt to reveal the role of these SNPs in somatic tumor progression. The risk allele of rs6983267 at 8q24 was favored in the tumors significantly more often than the neutral allele, indicating that this germline variant is somatically selected for. No imbalance targeting the risk allele was observed in the remaining loci, suggesting that most of the low-penetrance CRC SNPs mainly play a role in the early stages of the neoplastic process. The ten SNPs were further analyzed in 788 CRC cases, 97 of which had a family history of CRC, to evaluate their combined contribution. A significant association appeared between the overall number of risk alleles and familial CRC and these ten SNPs seem to explain around 9% of the familial clustering of CRC. Finding more CRC susceptibility alleles may facilitate individualized risk prediction and cancer prevention in the future. Microsatellite instability (MSI), resulting from defective mismatch repair function, is a hallmark of Lynch syndrome and observed in a subset of all CRCs. Our aim was to identify microsatellite frameshift mutations that inactivate tumor suppressor genes in MSI CRCs. By sequencing microsatellite repeats of underexpressed genes we found six novel MSI target genes that were frequently mutated in 100 MSI CRCs: 51% in GLYR1, 47% in ABCC5, 43% in WDTC1, 33% in ROCK1, 30% in OR51E2, and 28% in TCEB3. Immunohistochemical staining of GLYR1 revealed defective protein expression in homozygously mutated tumors, providing further support for the loss of function hypothesis. Another mutation screening effort sought to identify MSI target genes with putative oncogenic functions. Microsatellites were similarly sequenced in genes that were overexpressed and, upon mutation, predicted to avoid nonsense-mediated mRNA decay. The mitotic checkpoint kinase TTK harbored protein-elongating mutations in 59% of MSI CRCs and the mutant protein was detected in heterozygous MSI CRC cells. No checkpoint dysregulation or defective protein localization was observable however, and the biological relevance of this mutation may hence be related to other mechanisms. In conclusion, these two large-scale and unbiased efforts identified frequently mutated genes that are likely to contribute to the development of this cancer type and may be utilized in developing diagnostic and therapeutic applications.

The elastic manifestation of a spin-glass transition: a low-frequency study

The authors report here the first measurements of low-frequency dynamic elastic properties of a spin glass (Fe59Ni21Cr20) across the transition temperature (Tg approximately=16 K). A minimum in the sound velocity (V) and a maximum in the internal friction (Q-1) were found at temperatures close to but below Tg. The elastic data were compared with the AC susceptibility data taken at similar frequency.