Parallel-Interference-Cancellation-Assisted Decision-Directed Channel Estimation for OFDM Systems using Multiple Transmit Antennas

The number of transmit antennas that can be employed in the context of least-squares (LS) channel estimation contrived for orthogonal frequency division multiplexing (OFDM) systems employing multiple transmit antennas is limited by the ratio of the number of subcarriers and the number of significant channel impulse response (CIR)-related taps. In order to allow for more complex scenarios in terms of the number of transmit antennas and users supported, CIR-related tap prediction-filtering-based parallel interference cancellation (PIC)-assisted decision-directed channel estimation (DDCE) is investigated. New explicit expressions are derived for the estimator’s mean-square error (MSE), and a new iterative procedure is devised for the offline optimization of the CIR-related tap predictor coefficients. These new expressions are capable of accounting for the estimator’s novel recursive structure. In the context of our performance results, it is demonstrated, for example, that the estimator is capable of supporting L = 16 transmit antennas, when assuming K = 512 subcarriers and K0 = 64 significant CIR taps, while LS-optimized DDCE would be limited to employing L = 8 transmit antennas. Index Terms—Decision-directed channel estimation (DDCE), multiple transmit antennas, orthogonal frequency division multiplexing (OFDM), parallel interference cancellation (PIC)

History of contact and change in the Goroka Valley, Central Highlands of New Guinea, 1934-1949

The thesis traces the interaction of the Goroka Valley people with European and coastal New Guinean intruders during the pacification stage of contact and change. In this 15 year period the people moved from a traditional subsistence culture to the threshold of a modern, European-influenced technological society. The contact experiences of the inhabitants of the Valley and the outsiders who influenced them are examined, using both oral and documentary sources. A central theme of this study is the attempts by Europeans and their coastal New Guinean collaborators to achieve the pacification of a people for whom warfare has been described as \u27the dominant orientation\u27. The newcomers saw pacification as being inextricably linked with social, economic and religious transformation, and consequently it was pursued by patrol officers, missionaries and soldiers alike. Following an introductory chapter outlining the pre-contact and early-contact history of the Goroka Valley people, there is a discussion of the causes of tribal fighting in Highlands communities and two case studies of violent events which, although occurring beyond the Goroka Valley, had important consequences for those who lived within its bounds. The focus then shifts to the first permanent settlement of the agents of change -initially these were coastal New Guinean evangelists and policemen - and their impact on the local people. A period of consolidation is then described, as both government and missions established a permanent \u27European presence in the Valley\u27. This period was characterised by vigorous pacification coupled with the introduction of innovations in health and education, agriculture, technology, law and religion. The gradual transformation of Goroka Valley society as a result of the people\u27s interaction with the newcomers was abruptly accelerated in 1943, when many hundreds of Allied soldiers occupied the Valley in anticipation of a threatened Japanese invasion. Village life was disrupted as men were conscripted as carriers and labourers and whole communities were obliged to grow food to assist the Allied war effort. Those living close to military airfields-and camps were subject to Japanese aerial attacks and the entire population was exposed to an epidemic of bacillary dysentery introduced by the combatants. However the War also brought some positive effects, including paradoxically, the almost total cessation of tribal fighting, the construction of an ail-weather airstrip at Goroka which ensured its future as a town and administrative and commercial centre, and the compulsory growing of vegetables, coffee, etc, which laid the foundations for a cash economy and material prosperity. The final chapter examines the aftermath of military occupation, the return of civil administration and the implementation of social and economic policies which brought the Goroka Valley people into the rapid-development phase of contact. By 1949 Gorokans were ready to channel their aggressive energies into commercial competitiveness and adopt a cash-crop economy, to accept the European rule of law, to take advantage of Western innovations in medicine, education, transport and communications, to seek employment opportunities at home and in other parts of the country and to modify their primal world view with European religious and secular values. A Stone Age people was in process of being transformed into a modern society

Numerical simulation of heavy fermions in an SU(2)_L x SU(2)_R symmetric Yukawa model

An exploratory numerical study of the influence of heavy fermion doublets on the mass of the Higgs boson is performed in the decoupling limit of a chiral $\rm SU(2)_L \otimes SU(2)_R$ symmetric Yukawa model with mirror fermions. The behaviour of fermion and boson masses is investigated at infinite bare quartic coupling on $4^3 \cdot 8$, $6^3 \cdot 12$ and $8^3 \cdot 16$ lattices. A first estimate of the upper bound on the renormalized quartic coupling as a function of the renormalized Yukawa-coupling is given.Comment: 15 pp + 11 Figures appended as Postscript file

Sequence analysis and genomic organization of Aphid lethal paralysis virus: a new member of the family Dicistroviridae

The complete nucleotide sequence of the genomic RNA of an aphid-infecting virus, Aphid lethal paralysis virus (ALPV), has been determined. The genome is 9812 nt in length and contains two long open reading frames (ORFs), which are separated by an intergenic region of 163 nt. The first ORF (5' ORF) is preceded by an untranslated leader sequence of 506 nt, while an untranslated region of 571 nt follows the second ORF (3' ORF). The deduced amino acid sequences of the 5' ORF and 3' ORF products respectively showed similarity to the non-structural and structural proteins of members of the newly recognized genus Cripavirus (family Dicistroviridae). On the basis of the observed sequence similarities and identical genome organization, it is proposed that ALPV belongs to this genus. Phylogenetic analysis showed that ALPV is most closely related to Rhopalosiphum padi virus, and groups in a cluster with Drosophila C virus and Cricket paralysis virus, while the other members of this genus are more distantly related. Infectivity experiments showed that ALPV can not only infect aphid species but is also able to infect the whitefly Trialeurodes vaporariorum, extending its host range to another family of the order Hemipter

Self-consistent bounces in two dimensions

We compute bounce solutions describing false vacuum decay in a Phi**4 model in two dimensions in the Hartree approximation, thus going beyond the usual one-loop corrections to the decay rate. We use zero energy mode functions of the fluctuation operator for the numerical computation of the functional determinant and the Green's function. We thus avoid the necessity of discretizing the spectrum, as it is necessary when one uses numerical techniques based on eigenfunctions. Regularization is performed in analogy of standard perturbation theory; the renormalization of the Hartree approximation is based on the two-particle point-irreducible (2PPI) scheme. The iteration towards the self-consistent solution is found to converge for some range of the parameters. Within this range we find the corrections to the leading one-loop approximation to be relatively small, not exceeding one order of magnitude in the total transition rate.Comment: 30 pages, 12 figure

Transcriptional regulation and responses in filamentous fungi exposed to lignocellulose

Biofuels derived from lignocellulose are attractive alternative fuels but their production suffers from a costly and inefficient saccharification step that uses fungal enzymes. One route to improve this efficiency is to understand better the transcriptional regulation and responses of filamentous fungi to lignocellulose. Sensing and initial contact of the fungus with lignocellulose is an important aspect. Differences and similarities in the responses of fungi to different lignocellulosic substrates can partly be explained with existing understanding of several key regulators and their mode of action, as will be demonstrated for Trichoderma reesei, Neurospora crassa and Aspergillus spp. The regulation of genes encoding Carbohydrate Active enZymes (CAZymes) is influenced by the presence of carbohydrate monomers and short oligosaccharides, as well as the external stimuli of pH and light. We explore several important aspects of the response to lignocellulose that are not related to genes encoding CAZymes, namely the regulation of transporters, accessory proteins and stress responses. The regulation of gene expression is examined from the perspective of mixed cultures and models are presented for the nature of the transcriptional basis for any beneficial effects of such mixed cultures. Various applications in biofuel technology are based on manipulating transcriptional regulation and learning from fungal responses to lignocelluloses. Here we critically access the application of fungal transcriptional responses to industrial saccharification reactions. As part of this chapter, selected regulatory mechanisms are also explored in more detail

Drought reduces transmission of Turnip yellows virus , an insect-vectored circulative virus

Application of a severe water deficit to Arabidopsis thaliana plants infected with a mutant of Turnip yellows virus (TuYV, Family Luteoviridae) triggers a significant alteration of several plant phenology traits and strongly reduces the transmission efficiency of the virus by aphids. Although virus accumulation in water-stressed plants was similar to that in plants grown under well-watered conditions, virus accumulation was reduced in aphids fed on plant under water deficit. These results suggest alteration of the aphid feeding behavior on plants under water deficit