Impact of Phase Noise in MIMO-OFDM Systems

As MIMO-OFDM systems gain in popularity and move towards commercialization, the impact of analog hardware impairments need to be addressed to ensure these systems achieve the significant capacity/throughput gains they are capable of. In this paper we discuss the impact of correlated and uncorrelated phase noise on MIMO-OFDM systems. Where transmit (or receive) antennas are not colocated the phase noise is uncorrelated. Even in systems where the antennas at the transmitter/receiver are co-located, the multiple RF chains could have dedicated PLLs which introduce uncorrelated phase noise. We compare the performance degradation due to phase noise and show the impact of correcting phase noise in both these situations

Pollen loncevity in ecologically different zones of Western Kenya

Maize (Zea mays L.) is the most important staple crop in Kenya with the small holder farming systems accounting for about 75-80% of the total production. Most of the small-scale farmers plant locally adaptedlandraces and there are concerns about the possible contamination of these through geneflow from novel varieties, including the transgenics. The survival of pollen after dehiscence is an important factor affecting the geneflow. Studies were conducted to investigate the duration of pollen viability in two locations in western Kenya - Eldoret and Kakamega, representing the highland tropical and moist  mid-altitude/transitional zones, respectively. Pollen was collected at dehiscence and exposed as a thin layer in the open air for 0 (control), 15, 30, 60, 120 and 240 minutes. Pollen viability was assessed by measuring the seed set after pollination, scoring percentage pollen color change and percentage pollen germination. Pollen maintained viability for 120 minutes after dehiscence in Eldoret (T=23-240C; RH=45-55%; Ø=-109 to -82 MPa) and for 240 minutes in Kakamega (T=25-270C; RH=68-83%; Ø=-53 to -26 MPa). The differences in pollen longevity were attributed to the differences in atmospheric waterpotential between the two locations. The results suggest that the likelihood of genetic contamination of the landraces through geneflow from novel varieties is higher in the moist mid-altitude zones than in the highland tropical zones of Kenya

The transcription T-bet is required for optimal proinflammatory trafficking of CD4+ T cells

Background: The transcription factor T-bet is a critical regulator of Th1 effector function. Animals deficient in T-bet are protected from a variety of inflammatory diseases, including systemic lupus erythematosus and inflammatory arthritis. An essential function of Th1 cells is the ability to traffic appropriately to sites of inflammation, which is largely dependent on the expression of specific selectin ligands and chemokine receptors. We therefore hypothesised that T-bet would modulate lymphocyte trafficking in vitro and in vivo by direct regulation of both selectin binding and chemokine function. Methods: Balb/c mice deficient in, or transgenic for, T-bet had been generated previously. T-bet$^{-/-}$ × DO11.10 TCR and T-bet$^{-/-}$ × IFN$^{-/-}$ mice were generated by backcrossing for >10 generations. CD4$^+$ T cells were generated from primary lymph nodes from all these mice by positive selection and stimulation with appropriate antigen. Functional analysis used the following four methods: adoptive transfer into WT Balb/c mice, which were then injected with OVA, cells were harvested from the spleen, lymph node and peritoneum; selectin binding, interactions with immoblised P-selectin and E-selectin under conditions of laminar flow were examined in a parallel plate flow chamber; expression of selectin ligands, using flow cytometry, real-time PCR and 35S incorporation; and chemokine receptor expression and function, using flow cytometry, real-time PCR, transwell chemotaxis and endothelial binding under flow conditions. Results: Selective migration of T-bet$^{-/-}$ CD4$^+$ T cells in a Th1-dependent model of peritoneal inflammation was completely abrogated. Further investigation revealed that this effect was due to a 50% reduction in binding to P-selectin but not E-selectin under in vitro flow conditions and that this was as a result of impaired tyrosine sulfation of PSGL-1. In addition, mRNA and surface expression of CXCR3, but not CCR5, was reduced and this was associated with a reduction in both transwell chemotaxis and binding to endothelial cells. Retroviral transfer experiments of T-bet cDNA into T-bet$^{-/-}$ and T-bet$^{-/-}$ × IFN$^{-/-}$ cells demonstrated that these effects were independent of interferon. Conclusions: These data establish that T-bet imprints a specific migratory program onto developing CD4$^+$ cells via control of PSGL-1 sulfation (and thus P-selectin binding) and CXCR3 expression and function. Furthermore, as E-selectin and CCR5 binding are unimpaired, this reveals a level of control on trafficking of Th1 lymphocytes not recognised by previous paradigms

Probing top charged-Higgs production using top polarization at the Large Hadron Collider

We study single top production in association with a charged Higgs in the type II two Higgs doublet model at the Large Hadron Collider. The polarization of the top, reflected in the angular distributions of its decay products, can be a sensitive probe of new physics in its production. We present theoretically expected polarizations of the top for top charged-Higgs production, which is significantly different from that in the closely related process of t-W production in the Standard Model. We then show that an azimuthal symmetry, constructed from the decay lepton angular distribution in the laboratory frame, is a sensitive probe of top polarization and can be used to constrain parameters involved in top charged-Higgs production.Comment: 22 pages, 18 Figures, Discussions about backgrounds and NLO corrections added, figures modified, references added, Version published in JHE

Genome-Wide Association Study of Human Immunodeficiency Virus (HIV)-1 Coreceptor Usage in Treatment-Naive Patients from An AIDS Clinical Trials Group Study

OBJECTIVES: We conducted a genome-wide association study to explore whether common host genetic variants (>5% frequency) were associated with presence of virus able to use CXCR4 for entry. METHODS: Phenotypic determination of human immunodeficiency virus (HIV)-1 coreceptor usage was performed on pretreatment plasma HIV-1 samples from treatment-naive participants in AIDS Clinical Trials Group A5095, a study of initial antiretroviral regimens. Associations between genome-wide single-nucleotide polymorphisms (SNPs), CCR5 Δ32 genotype, and human leukocyte antigen (HLA) class I alleles and viral coreceptor usage were explored. RESULTS: Viral phenotypes were obtained from 593 patients with available genome-wide SNP data. Forty-four percent of subjects had virus capable of using CXCR4 for entry as determined by phenotyping. Overall, no associations, including those between polymorphisms in genes encoding viral coreceptors and their promoter regions or in HLA genes previously associated with HIV-1 disease progression, passed the statistical threshold for genome-wide significance (P < 5.0 × 10(-8)) in any comparison. However, the presence of viruses able to use CXCR4 for entry was marginally associated with the CCR5 Δ32 genotype in the nongenome-wide analysis. CONCLUSIONS: No human genetic variants were significantly associated with virus able to use CXCR4 for entry at the genome-wide level. Although the sample size had limited power to definitively exclude genetic associations, these results suggest that host genetic factors, including those that influence coreceptor expression or the immune pressures leading to viral envelope diversity, are either rare or have only modest effects in determining HIV-1 coreceptor usage

Growth hormone as concomitant treatment in severe fibromyalgia associated with low IGF-1 serum levels. A pilot study

<p>Abstract</p> <p>Background</p> <p>There is evidence of functional growth hormone (GH) deficiency, expressed by means of low insulin-like growth factor 1 (IGF-1) serum levels, in a subset of fibromyalgia patients. The efficacy of GH versus placebo has been previously suggested in this population. We investigated the efficacy and safety of low dose GH as an adjunct to standard therapy in the treatment of severe, prolonged and well-treated fibromyalgia patients with low IGF-1 levels.</p> <p>Methods</p> <p>Twenty-four patients were enrolled in a randomized, open-label, best available care-controlled study. Patients were randomly assigned to receive either 0.0125 mg/kg/d of GH subcutaneously (titrated depending on IGF-1) added to standard therapy or standard therapy alone during one year. The number of tender points, the Fibromyalgia Impact Questionnaire (FIQ) and the EuroQol 5D (EQ-5D), including a Quality of Life visual analogic scale (EQ-VAS) were assessed at different time-points.</p> <p>Results</p> <p>At the end of the study, the GH group showed a 60% reduction in the mean number of tender points (pairs) compared to the control group (p < 0.05; 3.25 ± 0.8 <it>vs</it>. 8.25 ± 0.9). Similar improvements were observed in FIQ score (p < 0.05) and EQ-VAS scale (p < 0.001). There was a prompt response to GH administration, with most patients showing improvement within the first months in most of the outcomes. The concomitant administration of GH and standard therapy was well tolerated, and no patients discontinued the study due to adverse events.</p> <p>Conclusion</p> <p>The present findings indicate the advantage of adding a daily GH dose to the standard therapy in a subset of severe fibromyalgia patients with low IGF-1 serum levels.</p> <p>Trial Registration</p> <p>NCT00497562 (ClinicalTrials.gov).</p

On measurement of top polarization as a probe of ttˉt \bar t production mechanisms at the LHC

In this note we demonstrate the use of top polarization in the study of $t \bar t$ resonances at the LHC, in the possible case where the dynamics implies a non-zero top polarization. As a probe of top polarization we construct an asymmetry in the decay-lepton azimuthal angle distribution (corresponding to the sign of $\cos\phi_\ell$) in the laboratory. The asymmetry is non-vanishing even for a symmetric collider like the LHC, where a positive $z$ axis is not uniquely defined. The angular distribution of the leptons has the advantage of being a faithful top-spin analyzer, unaffected by possible anomalous $tbW$ couplings, to linear order. We study, for purposes of demonstration, the case of a $Z'$ as might exist in the little Higgs models. We identify kinematic cuts which ensure that our asymmetry reflects the polarization in sign and magnitude. We investigate possibilities at the LHC with two energy options: $\sqrt{s} = 14$ TeV and $\sqrt{s} = 7$ TeV, as well as at the Tevatron. At the LHC the model predicts net top quark polarization of the order of a few per cent for $M_{Z'} \simeq 1200$ GeV, being as high as $10$ for a smaller mass of the $Z'$ of $700$ GeV and for the largest allowed coupling in the model, the values being higher for the $7$ TeV option. These polarizations translate to a deviation from the standard-model value of azimuthal asymmetry of up to about $4$ ($7$) for $14$ ($7$) TeV LHC, whereas for the Tevatron, values as high as $12$ are attained. For the $14$ TeV LHC with an integrated luminosity of 10 fb$^{-1}$, these numbers translate into a $3 \sigma$ sensitivity over a large part of the range $500 \lesssim M_{Z'} \lesssim 1500$ GeV.Comment: 28 page, LaTeX, requires JHEP style file, 12 figures. Typos corrected and references adde

Thermodynamics of a class of non-asymptotically flat black holes in Einstein-Maxwell-Dilaton theory

We analyse in detail the thermodynamics in the canonical and grand canonical ensembles of a class of non-asymptotically flat black holes of the Einstein-(anti) Maxwell-(anti) Dilaton theory in 4D with spherical symmetry. We present the first law of thermodynamics, the thermodynamic analysis of the system through the geometrothermodynamics methods, Weinhold, Ruppeiner, Liu-Lu-Luo-Shao and the most common, that made by the specific heat. The geometric methods show a curvature scalar identically zero, which is incompatible with the results of the analysis made by the non null specific heat, which shows that the system is thermodynamically interacting, does not possess extreme case nor phase transition. We also analyse the local and global stability of the thermodynamic system, and obtain a local and global stability for the normal case for 0<\gamma<1 and for other values of \gamma, an unstable system. The solution where \gamma=0 separates the class of locally and globally stable solutions from the unstable ones.Comment: 18 pages, version accepted for publication in General Relativity and Gravitatio