291 research outputs found

    A Search for Z Boson Pair Production at the Fermilab Tevatron Collider

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    This dissertation describes a search for Z boson pair production decaying into four muon, four electron, and two muon two electron final states with approximately 1 fb^-1 of data at the Fermilab Tevatron Collider at sqrt(s)=1.96 TeV. The small cross section times branching ratio for each channel mandated a thorough study of the acceptance and efficiencies. After optimization, 1.7 +- 0.1 events are expected for Standard Model production with a background of 0.13 +- 0.03 events. One event was found in the two muons two electron channel. A cross section limit of 4.4 pb is determined at a 95% confidence level for Standard Model production. Additionally, one parameter and two parameter 95% C.L. limits are found for the anomalous neutral trilinear gauge couplings ZZZ* and ZZgamma*. The one parameter 95% C.L. coupling limits with a form factor scale of 1.2~TeV are: -0.28 f_40^Z<0.28, -0.31<f_50^Z<0.29, -0.26<f_40^gamma<0.26, and -0.30<f_50^gamma<0.28

    Diffraction line profile analysis of 3D wedge samples of Ti-6Al-4V fabricated using four different additive manufacturing processes

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    Wedge‐-shaped samples were manufactured by four different Additive Manufacturing (AM) processes, namely selective laser melting (SLM), electron beam melting (EBM), direct metal deposition (DMD), and wire and arc additive manufacturing (WAAM), using Ti‐-6Al‐-4V as the feed material. A high‐-resolution powder diffractometer was used to measure the diffraction patterns of the samples whilst rotated about two axes to collect detected neutrons from all possible lattice planes. The diffraction pattern of a LaB6 standard powder sample was also measured to characterize the instrumental broadening and peak shapes necessary for the Diffraction Line Profile Analysis. The line profile analysis was conducted using the extended Convolution Multiple Whole Profile (eCMWP) procedure. Once analyzed, it was found that there was significant variation in the dislocation densities between the SLMed and the EBMed samples, although having a similar manufacturing technique. While the samples fabricated via WAAM and the DMD processes showed almost similar dislocation densities, they were, however, different in comparison to the other two AM processes, as expected. The hexagonal (HCP) crystal structure of the predominant α‐-Ti phase allowed a breakdown of the percentage of the Burgers\u27 vectors possible for this crystal structure. All four techniques exhibited different combinations of the three possible Burgers\u27 vectors, and these differences were attributed to the variation in the cooling rates experienced by the parts fabricated using these AM processes

    Mass Spectrometric Immunoassay for the qualitative and quantitative analysis of the cytokine Macrophage Migration Inhibitory Factor (MIF)

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    BACKGROUND: The cytokine MIF (Macrophage Migration Inhibitory Factor) has diverse physiological roles and is present at elevated concentrations in numerous disease states. However, its molecular heterogeneity has not been previously investigated in biological samples. Mass Spectrometric Immunoassay (MSIA) may help elucidate MIF post-translational modifications existing in vivo and provide additional clarity regarding its relationship to diverse pathologies. RESULTS: In this work, we have developed and validated a fully quantitative MSIA assay for MIF, and used it in the discovery and quantification of different proteoforms of MIF in serum samples, including cysteinylated and glycated MIF. The MSIA assay had a linear range of 1.56-50 ng/mL, and exhibited good precision, linearity, and recovery characteristics. The new assay was applied to a small cohort of human serum samples, and benchmarked against an MIF ELISA assay. CONCLUSIONS: The quantitative MIF MSIA assay provides a sensitive, precise and high throughput method to delineate and quantify MIF proteoforms in biological samples

    Remodeling of Purinergic Receptor-Mediated Ca2+ Signaling as a Consequence of EGF-Induced Epithelial-Mesenchymal Transition in Breast Cancer Cells

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    Background The microenvironment plays a pivotal role in tumor cell proliferation, survival and migration. Invasive cancer cells face a new set of environmental challenges as they breach the basement membrane and colonize distant organs during the process of metastasis. Phenotypic switching, such as that which occurs during epithelial-mesenchymal transition (EMT), may be associated with a remodeling of cell surface receptors and thus altered responses to signals from the tumor microenvironment. Methodology/Principal Findings We assessed changes in intracellular Ca 2+ in cells loaded with Fluo-4 AM using a fluorometric imaging plate reader (FLIPR TETRA) and observed significant changes in the potency of ATP (EC 50 0.175 ÎŒM (-EGF) versus 1.731 ÎŒM (+EGF), P<0.05), and the nature of the ATP-induced Ca 2+ transient, corresponding with a 10-fold increase in the mesenchymal marker vimentin (P<0.05). We observed no change in the sensitivity to PAR2-mediated Ca 2+ signaling, indicating that these alterations are not simply a consequence of changes in global Ca 2+ homeostasis. To determine whether changes in ATP-mediated Ca 2+ signaling are preceded by alterations in the transcriptional profile of purinergic receptors, we analyzed the expression of a panel of P2X ionotropic and P2Y metabotropic purinergic receptors using real-time RT-PCR and found significant and specific alterations in the suite of ATP-activated purinergic receptors during EGF-induced EMT in breast cancer cells. Our studies are the first to show that P2X 5 ionotropic receptors are enriched in the mesenchymal phenotype and that silencing of P2X 5 leads to a significant reduction (25%, P<0.05) in EGF-induced vimentin protein expression. Conclusions The acquisition of a new suite of cell surface purinergic receptors is a feature of EGF-mediated EMT in MDA-MB-468 breast cancer cells. Such changes may impart advantageous phenotypic traits and represent a novel mechanism for the targeting of cancer metastasis

    Design, Performance, and Calibration of CMS Hadron-Barrel Calorimeter Wedges

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    Extensive measurements have been made with pions, electrons and muons on four production wedges of the Compact Muon Solenoid (CMS) hadron barrel (HB) calorimeter in the H2 beam line at CERN with particle momenta varying from 20 to 300 GeV/c. Data were taken both with and without a prototype electromagnetic lead tungstate crystal calorimeter (EB) in front of the hadron calorimeter. The time structure of the events was measured with the full chain of preproduction front-end electronics running at 34 MHz. Moving-wire radioactive source data were also collected for all scintillator layers in the HB. These measurements set the absolute calibration of the HB prior to first pp collisions to approximately 4%

    Synchronization and Timing in CMS HCAL

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    The synchronization and timing of the hadron calorimeter (HCAL) for the Compact Muon Solenoid has been extensively studied with test beams at CERN during the period 2003-4, including runs with 40 MHz structured beam. The relative phases of the signals from different calorimeter segments are timed to 1 ns accuracy using a laser and equalized using programmable delay settings in the front-end electronics. The beam was used to verify the timing and to map out the entire range of pulse shapes over the 25 ns interval between beam crossings. These data were used to make detailed measurements of energy-dependent time slewing effects and to tune the electronics for optimal performance
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