7,231 research outputs found
Flattening of the Phillips Curve and the Role of Oil Price: An Unobserved Components Model for the USA and Australia
We use the unobserved components model of Harvey (1989 and 2011) to estimate the Phillips curve (PC) for the USA and Australia, by augmenting it with oil prices. We found that the level coefficient of inflation and the coefficient of demand pressure have declined and contributed to the flattening of the Phillips curve. But the coefficient of oil prices has increased and has partly offset these effects. Therefore, oil prices are likely to play a significant role in future inflation rates.
Quantum Fourier transform revisited
The fast Fourier transform (FFT) is one of the most successful numerical algorithms of the 20th century and has found numerous applications in many branches of computational science and engineering. The FFT algorithm can be derived from a particular matrix decomposition of the discrete Fourier transform (DFT) matrix. In this paper, we show that the quantum Fourier transform (QFT) can be derived by further decomposing the diagonal factors of the FFT matrix decomposition into products of matrices with Kronecker product structure. We analyze the implication of this Kronecker product structure on the discrete Fourier transform of rank-1 tensors on a classical computer. We also explain why such a structure can take advantage of an important quantum computer feature that enables the QFT algorithm to attain an exponential speedup on a quantum computer over the FFT algorithm on a classical computer. Further, the connection between the matrix decomposition of the DFT matrix and a quantum circuit is made. We also discuss a natural extension of a radix-2 QFT decomposition to a radix-d QFT decomposition. No prior knowledge of quantum computing is required to understand what is presented in this paper. Yet, we believe this paper may help readers to gain some rudimentary understanding of the nature of quantum computing from a matrix computation point of view
The Effect of Particulate Air Pollution on Emergency Admissions for Myocardial Infarction: A Multicity Case-Crossover Analysis
Recently, attention has focused on whether particulate air pollution is a specific trigger of myocardial infarction (MI). The results of several studies of single locations assessing the effects of ambient particular matter on the risk of MI have been disparate. We used a multicity case-crossover study to examine risk of emergency hospitalization associated with fine particulate matter (PM) with aerodynamic diameter < 10 μm (PM(10)) for > 300,000 MIs during 1985–1999 among elderly residents of 21 U.S. cities. We used time-stratified controls matched on day of the week or on temperature to detect possible residual confounding by weather. Overall, we found a 0.65% [95% confidence interval (CI), 0.3–1.0%] increased risk of hospitalization for MI per 10 μg/m(3) increase in ambient PM(10) concentration. Matching on apparent temperature yielded a 0.64% increase in risk (95% CI, 0.1–1.2%). We found that the effect size for PM(10) doubled for subjects with a previous admission for chronic obstructive pulmonary disease or a secondary diagnosis of pneumonia, although these differences did not achieve statistical significance. There was a weaker indication of a larger effect on males but no evidence of effect modification by age or the other diagnoses. We also found that the shape of the exposure–response relationship between MI hospitalizations and PM(10) is almost linear, but with a steeper slope at levels of PM(10) < 50 μg/m(3). We conclude that increased concentrations of ambient PM(10) are associated with increased risk of MI among the elderly
Human immunodeficiency virus infection of the human thymus and disruption of the thymic microenvironment in the SCID-hu mouse.
Infection with the human immunodeficiency virus (HIV) results in immunosuppression and depletion of circulating CD4+ T cells. Since the thymus is the primary organ in which T cells mature it is of interest to examine the effects of HIV infection in this tissue. HIV infection has been demonstrated in the thymuses of infected individuals and thymocytes have been previously demonstrated to be susceptible to HIV infection both in vivo, using the SCID-hu mouse, and in vitro. The present study sought to determine which subsets of thymocytes were infected in the SCID-hu mouse model and to evaluate HIV-related alterations in the thymic microenvironment. Using two different primary HIV isolates, infection was found in CD4+/CD8+ double positive thymocytes as well as in both the CD4+ and CD8+ single positive subsets of thymocytes. The kinetics of infection and resulting viral burden differed among the three thymocyte subsets and depended on which HIV isolate was used for infection. Thymic epithelial (TE) cells were also shown to endocytose virus and to often contain copious amounts of viral RNA in the cytoplasm by in situ hybridization, although productive infection of these cells could not be definitively shown. Furthermore, degenerating TE cells were observed even without detection of HIV in the degenerating cells. Two striking morphologic patterns of infection were seen, involving either predominantly thymocyte infection and depletion, or TE cell involvement with detectable cytoplasmic viral RNA and/or TE cell toxicity. Thus, a variety of cells in the human thymus is susceptible to HIV infection, and infection with HIV results in a marked disruption of the thymic microenvironment leading to depletion of thymocytes and degeneration of TE cells
Multiple Parton Interactions in Z+jets production at the LHC. A comparison of factorized and non--factorized double parton distribution functions
We examine the contribution of Multiple Parton Interactions to Z+n-jets
production at the LHC, n=2,3,4, where the Z boson is assumed to decay
leptonically. We compare the results obtained with the correlated GS09 double
parton distribution function with those obtained with two instances of fully
factorized single parton distribution functions: MSTW2008LO and CTEQ6LO. It
appears quite feasible to measure the MPI contribution to Z+2/3/4 jets already
in the first phase of the LHC with a total luminosity of one inverse femtobarn
at 7 TeV. If as expected the trigger threshold for single photons is around 80
GeV, Z+2-jets production may well turn out to be more easily observable than
the gamma+3-jets channel. The MPI cross section is dominated by relatively soft
events with two jets balancing in transverse momentum.Comment: 15 pages, 3 plot
The growth exponent for planar loop-erased random walk
We give a new proof of a result of Kenyon that the growth exponent for
loop-erased random walks in two dimensions is 5/4. The proof uses the
convergence of LERW to Schramm-Loewner evolution with parameter 2, and is valid
for irreducible bounded symmetric random walks on any two-dimensional discrete
lattice.Comment: 62 pages, 7 figures; fixed typos, added reference
Evaluation of the diagnostic accuracy of prototype rapid tests for human African trypanosomiasis
Peer reviewedPublisher PD
Comparative genomics between Trichomonas tenax and Trichomonas vaginalis: CAZymes and candidate virulence factors
Introduction: The oral trichomonad Trichomonas tenax is increasingly 82 appreciated as a likely contributor to periodontitis, a chronic inflammatory 83 disease induced by dysbiotic microbiota, in humans and domestic animals and 84 is strongly associated with its worst prognosis. Our current understanding of 85 the molecular basis of T. tenax interactions with host cells and the microbiota 86 of the oral cavity are still rather limited. One laboratory strain of T. tenax (Hs- 87 4:NIH/ATCC 30207) can be grown axenically and two draft genome assemblies 88 have been published for that strain, although the structural and functional 89 annotation of these genomes is not available. 90Methods: GenSAS and Galaxy were used to annotate two publicly available 91 draft genomes for T. tenax, with a focus on protein-coding genes. A custom 92 pipeline was used to annotate the CAZymes for T. tenax and the human 93 sexually transmitted parasite Trichomonas vaginalis, the most well-characterized 94 trichomonad. A combination of bioinformatics analyses was used to screen for 95 homologs of T. vaginalis virulence and colonization factors within the T. tenax 96 annotated proteins. 97Results: Our annotation of the two T. tenax draft genome sequences and their 98 comparison with T. vaginalis proteins provide evidence for several candidate 99 virulence factors. These include candidate surface proteins, secreted proteins 100 and enzymes mediating potential interactions with host cells and/or members 101 of the oral microbiota. The CAZymes annotation identified a broad range of 102 glycoside hydrolase (GH) families, with the majority of these being shared 103between the two Trichomonas species. 104 105 Discussion: The presence of candidate T. tenax virulence genes supports the 106hypothesis that this species is associated with periodontitis through direct and 107 indirect mechanisms. Notably, several GH proteins could represent potential new 108 virulence factors for both Trichomonas species. These data support a model 109 where T. tenax interactions with host cells and members of the oral microbiota 110 could synergistically contribute to the damaging inflammation characteristic of 111 periodontitis, supporting a causal link between T. tenax and periodontitis
Telomere disruption results in non-random formation of de novo dicentric chromosomes involving acrocentric human chromosomes
Copyright: © 2010 Stimpson et al.Genome rearrangement often produces chromosomes with two centromeres (dicentrics) that are inherently unstable because of bridge formation and breakage during cell division. However, mammalian dicentrics, and particularly those in humans, can be quite stable, usually because one centromere is functionally silenced. Molecular mechanisms of centromere inactivation are poorly understood since there are few systems to experimentally create dicentric human chromosomes. Here, we describe a human cell culture model that enriches for de novo dicentrics. We demonstrate that transient disruption of human telomere structure non-randomly produces dicentric fusions involving acrocentric chromosomes. The induced dicentrics vary in structure near fusion breakpoints and like naturally-occurring dicentrics, exhibit various inter-centromeric distances. Many functional dicentrics persist for months after formation. Even those with distantly spaced centromeres remain functionally dicentric for 20 cell generations. Other dicentrics within the population reflect centromere inactivation. In some cases, centromere inactivation occurs by an apparently epigenetic mechanism. In other dicentrics, the size of the alpha-satellite DNA array associated with CENP-A is reduced compared to the same array before dicentric formation. Extrachromosomal fragments that contained CENP-A often appear in the same cells as dicentrics. Some of these fragments are derived from the same alpha-satellite DNA array as inactivated centromeres. Our results indicate that dicentric human chromosomes undergo alternative fates after formation. Many retain two active centromeres and are stable through multiple cell divisions. Others undergo centromere inactivation. This event occurs within a broad temporal window and can involve deletion of chromatin that marks the locus as a site for CENP-A maintenance/replenishment.This work was supported by the Tumorzentrum Heidelberg/Mannheim grant (D.10026941)and by March of Dimes Research Foundation grant #1-FY06-377 and NIH R01 GM069514
Strong Double Higgs Production at the LHC
The hierarchy problem and the electroweak data, together, provide a plausible
motivation for considering a light Higgs emerging as a pseudo-Goldstone boson
from a strongly-coupled sector. In that scenario, the rates for Higgs
production and decay differ significantly from those in the Standard Model.
However, one genuine strong coupling signature is the growth with energy of the
scattering amplitudes among the Goldstone bosons, the longitudinally polarized
vector bosons as well as the Higgs boson itself. The rate for double Higgs
production in vector boson fusion is thus enhanced with respect to its
negligible rate in the SM. We study that reaction in pp collisions, where the
production of two Higgs bosons at high pT is associated with the emission of
two forward jets. We concentrate on the decay mode hh -> WW^(*)WW^(*) and study
the semi-leptonic decay chains of the W's with 2, 3 or 4 leptons in the final
states. While the 3 lepton final states are the most relevant and can lead to a
3 sigma signal significance with 300 fb^{-1} collected at a 14 TeV LHC, the two
same-sign lepton final states provide complementary information. We also
comment on the prospects for improving the detectability of double Higgs
production at the foreseen LHC energy and luminosity upgrades.Comment: 54 pages, 26 figures. v2: typos corrected, a few comments and one
table added. Version published in JHE
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