200 research outputs found

    A Petri net simulation model for virtual construction of earthmoving operations

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    A common and extended Petri net simulation framework for virtual construction of earthmoving operations is developed to simulate dynamic changes of workflow and information flow in the earthmoving construction process and illustrate the constraint relationship between various operational equipment and construction restrictions. The proposed framework considers factors that influence earthmoving operations including randomness of construction activities, individual preference of equipment scheduling, and constraint relationship between equipment and construction environment. With the given equipment availability and project indirect cost, the framework can predict construction situation, equipment utilization rate, estimated duration and cost to achieve visualized and intelligent scheduling of virtual construction process in earthmoving operations. The simulation process is conducted on the CPNTools platform. The data required by the research were collected on-site in an actual case. The randomness of construction activities in earthmoving operations and main factors influencing construction are simulated. The sensitivity analysis for the model is carried out. The study will provide technical support and a management basis for equipment scheduling of earthmoving operations

    A Precise Measurement of the Muon Neutrino-Nucleon Inclusive Charged Current Cross-Section off an Isoscalar Target in the Energy Range 2.5 < E_\nu < 40 GeV by NOMAD

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    We present a measurement of the muon neutrino-nucleon inclusive charged current cross-section, off an isoscalar target, in the neutrino energy range 2.5Eν402.5 \leq E_\nu \leq 40 GeV. The significance of this measurement is its precision, ±4\pm 4% in 2.5Eν102.5 \leq E_\nu \leq 10 GeV, and ±2.6\pm 2.6% in 10Eν4010 \leq E_\nu \leq 40 GeV regions, where significant uncertainties in previous experiments still exist, and its importance to the current and proposed long baseline neutrino oscillation experiments.Comment: 14 pages, 3 figures, submitted to Phys.Lett.

    A Measurement of Coherent Neutral Pion Production in Neutrino Neutral Current Interactions in NOMAD

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    We present a study of exclusive neutral pion production in neutrino-nucleus Neutral Current interactions using data from the NOMAD experiment at the CERN SPS. The data correspond to 1.44×1061.44 \times 10^6 muon-neutrino Charged Current interactions in the energy range 2.5Eν3002.5 \leq E_{\nu} \leq 300 GeV. Neutrino events with only one visible π0\pi^0 in the final state are expected to result from two Neutral Current processes: coherent π0\pi^0 production, {\boldmath ν+Aν+A+π0\nu + {\cal A} \to \nu + {\cal A} + \pi^0} and single π0\pi^0 production in neutrino-nucleon scattering. The signature of coherent π0\pi^0 production is an emergent π0\pi^0 almost collinear with the incident neutrino while π0\pi^0's produced in neutrino-nucleon deep inelastic scattering have larger transverse momenta. In this analysis all relevant backgrounds to the coherent π0\pi^0 production signal are measured using data themselves. Having determined the backgrounds, and using the Rein-Sehgal model for the coherent π0\pi^0 production to compute the detection efficiency, we obtain {\boldmath 4630±522(stat)±426(syst)4630 \pm 522 (stat) \pm 426 (syst)} corrected coherent-π0\pi^0 events with Eπ00.5E_{\pi^0} \geq 0.5 GeV. We measure {\boldmath σ(νAνAπ0)=[72.6±8.1(stat)±6.9(syst)]×1040cm2/nucleus\sigma (\nu {\cal A} \to \nu {\cal A} \pi^0) = [ 72.6 \pm 8.1(stat) \pm 6.9(syst) ] \times 10^{-40} cm^2/nucleus}. This is the most precise measurement of the coherent π0\pi^0 production to date.Comment: 23 pages, 9 figures, accepted for publication in Phys. Lett.

    Observation of hard scattering in photoproduction events with a large rapidity gap at HERA

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    Events with a large rapidity gap and total transverse energy greater than 5 GeV have been observed in quasi-real photoproduction at HERA with the ZEUS detector. The distribution of these events as a function of the γp\gamma p centre of mass energy is consistent with diffractive scattering. For total transverse energies above 12 GeV, the hadronic final states show predominantly a two-jet structure with each jet having a transverse energy greater than 4 GeV. For the two-jet events, little energy flow is found outside the jets. This observation is consistent with the hard scattering of a quasi-real photon with a colourless object in the proton.Comment: 19 pages, latex, 4 figures appended as uuencoded fil

    Glycoprotein gene truncation in avian metapneumovirus subtype C isolates from the United States

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    The length of the published glycoprotein (G) gene sequences of avian metapneumovirus subtype-C (aMPV-C) isolated from domestic turkeys and wild birds in the United States (1996–2003) remains controversial. To explore the G gene size variation in aMPV-C by the year of isolation and cell culture passage levels, we examined 21 turkey isolates of aMPV-C at different cell culture passages. The early domestic turkey isolates of aMPV-C (aMPV/CO/1996, aMPV/MN/1a-b, and 2a-b/97) had a G gene of 1,798 nucleotides (nt) that coded for a predicted protein of 585 amino acids (aa) and showed >97% nt similarity with that of aMPV-C isolated from Canada geese. This large G gene got truncated upon serial passages in Vero cell cultures by deletion of 1,015 nt near the end of the open reading frame. The recent domestic turkey isolates of aMPV-C lacked the large G gene but instead had a small G gene of 783 nt, irrespective of cell culture passage levels. In some cultures, both large and small genes were detected, indicating the existence of a mixed population of the virus. Apparently, serial passage of aMPV-C in cell cultures and natural passage in turkeys in the field led to truncation of the G gene, which may be a mechanism of virus evolution for survival in a new host or environment

    A Search for Single Photon Events in Neutrino Interactions

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    We present a search for neutrino-induced events containing a single, exclusive photon using data from the NOMAD experiment at the CERN SPS where the average energy of the neutrino flux is 25\simeq 25 GeV. The search is motivated by an excess of electron-like events in the 200--475 MeV energy region as reported by the MiniBOONE experiment. In NOMAD, photons are identified via their conversion to e+ee^+e^- in an active target embedded in a magnetic field. The background to the single photon signal is dominated by the asymmetric decay of neutral pions produced either in a coherent neutrino-nucleus interaction, or in a neutrino-nucleon neutral current deep inelastic scattering, or in an interaction occurring outside the fiducial volume. All three backgrounds are determined {\it in situ} using control data samples prior to opening the `signal-box'. In the signal region, we observe {\bf 155} events with a predicted background of {\bf 129.2 ±\pm 8.5 ±\pm 3.3}. We interpret this as null evidence for excess of single photon events, and set a limit. Assuming that the hypothetical single photon has a momentum distribution similar to that of a photon from the coherent π0\pi^0 decay, the measurement yields an upper limit on single photon events, {\boldmath <4.0×104< 4.0 \times 10^{-4}} per \nm\ charged current event. Narrowing the search to events where the photon is approximately collinear with the incident neutrino, we observe {\bf 78} events with a predicted background of {\bf 76.6 ±\pm 4.9 ±\pm 1.9} yielding a more stringent upper limit, {\boldmath <1.6×104< 1.6 \times 10^{-4}} per \nm\ charged current event

    Observation of Events with an Energetic Forward Neutron in Deep Inelastic Scattering at HERA

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    In deep inelastic neutral current scattering of positrons and protons at the center of mass energy of 300 GeV, we observe, with the ZEUS detector, events with a high energy neutron produced at very small scattering angles with respect to the proton direction. The events constitute a fixed fraction of the deep inelastic, neutral current event sample independent of Bjorken x and Q2 in the range 3 · 10-4 \u3c xBJ \u3c 6 · 10-3 and 10 \u3c Q2 \u3c 100 GeV2

    Extraction of the gluon density of the proton at x

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    TGF-beta signaling in cancer metastasis

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    Cancer Signaling networks and Molecular Therapeutic

    The effect of genotype and in utero environment on interindividual variation in neonate DNA methylomes

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    Integrating the genotype with epigenetic marks holds the promise of better understanding the biology that underlies the complex interactions of inherited and environmental components that define the developmental origins of a range of disorders. The quality of the in utero environment significantly influences health over the lifecourse. Epigenetics, and in particular DNA methylation marks, have been postulated as a mechanism for the enduring effects of the prenatal environment. Accordingly, neonate methylomes contain molecular memory of the individual in utero experience. However, interindividual variation in methylation can also be a consequence of DNA sequence polymorphisms that result in methylation quantitative trait loci (methQTLs) and, potentially, the interaction between fixed genetic variation and environmental influences. We surveyed the genotypes and DNA methylomes of 237 neonates and found 1423 punctuate regions of the methylome that were highly variable across individuals, termed variably methylated regions (VMRs), against a backdrop of homogeneity. MethQTLs were readily detected in neonatal methylomes, and genotype alone best explained ?25% of the VMRs. We found that the best explanation for 75% of VMRs was the interaction of genotype with different in utero environments, including maternal smoking, maternal depression, maternal BMI, infant birth weight, gestational age, and birth order. Our study sheds new light on the complex relationship between biological inheritance as represented by genotype and individual prenatal experience and suggests the importance of considering both fixed genetic variation and environmental factors in interpreting epigenetic variation
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