177 research outputs found

    A Microfluidic Device for the Investigation of Rapid Gold Nanoparticle Formation in Continuous Turbulent Flow

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    A new setup with an integrated microfluidic chip with small dead time, high time resolution and compatibility with in situ X-ray absorption (XAS) measurements is presented. It can also be combined with a free liquid jet. By using the microfluidic chip the short reaction times from 2 to 20 milliseconds can be observed, beyond that an external cyclone mixer for extended observation times was applied. The reduction of gold ions with tetrakis(hydroxy-methyl)phosphonium (THPC) has been investigated in the microfluidic setup to monitor this reaction yielding small gold nanoparticles, requiring preferentially a free liquid jet

    Quartic Anomalous Couplings in γγ\gamma\gamma Colliders

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    We study the constraints on the vertices W+WZγW^+W^- Z\gamma, W+WγγW^+W^-\gamma\gamma, and ZZγγZZ\gamma\gamma that can be obtained from triple-gauge-boson production at the next generation of linear e+ee^+e^- colliders operating in the γγ\gamma\gamma mode. We analyze the processes γγW+WV\gamma\gamma \to W^+W^-V (V=ZV=Z, or γ\gamma) and show that these reactions increase the potential of e+ee^+e^- machines to search for anomalous four-gauge-boson interactions.Comment: 15 pages, Latex file using ReVteX, 4 uufiled figures include

    Probing Anomalous Quartic Couplings in e-gamma and gamma-gamma Colliders

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    We analyze the potential of the e+e- Linear Colliders, operating in the e-gamma and gamma-gamma modes, to probe anomalous quartic vector--boson interactions through the multiple production of W's and Z's. We examine all SU(2)LU(1)YSU(2)_L \otimes U(1)_Y chiral operators of order p^4 that lead to new four--gauge--boson interactions but do not alter trilinear vertices. We show that the e-gamma and gamma-gamma modes are able not only to establish the existence of a strongly interacting symmetry breaking sector but also to probe for anomalous quartic couplings of the order of 10^{-2} at 90% CL. Moreover, the information gathered in the e-gamma mode can be used to reduced the ambiguities of the e+e- mode.Comment: Revtex, 18 pages, 6 figure

    A Person-Centered Approach to Commitment Research: Theory, Research, and Methodology

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    There has been a recent increase in the application of person-centered research strategies in the investigation of workplace commitments. To date, research has focused primarily on the identification, within a population, of subgroups presenting different cross-sectional or longitudinal configurations of commitment mindsets (affective, normative, continuance) and/or targets (e.g., organization, occupation, supervisor), but other applications are possible. In an effort to promote a substantive-methodological synergy, we begin by explaining why some aspects of commitment theory are best tested using a person-centered approach. We then summarize the result of existing research and suggest applications to other research questions. Next, we turn our attention to methodological issues, including strategies for identifying the best profile structure, testing for invariance across samples, time, culture, etc., and incorporating other variables in the models to test theory regarding profile development, consequences, and change trajectories. We conclude with a discussion of the practical implications of taking a person-centered approach to the study of commitment as a complement to the more traditional variable-centered approach

    Triple Electroweak Gauge-Boson Production at Fermilab Tevatron Energies

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    We calculate the three gauge-boson production in the Standard Model at Fermilab Tevatron energies. At s=2\sqrt s=2 TeV in ppˉp\bar p collisions, the cross sections for the triple gauge-boson production are typically of order 10 femtobarns (fb). For the pure leptonic final states from the gauge-boson decays and with some minimal cuts on final state photons, the cross sections for ppˉW±γγ,Zγγp \bar p \rightarrow W^\pm \gamma\gamma, Z\gamma\gamma and W+WγW^+W^- \gamma processes are of order a few fb, resulting in a few dozen clean leptonic events for an integrated luminosity of 10 fb1^{-1}. The pure leptonic modes from other gauge-boson channels give significantly smaller rate. Especially, the trilepton modes from W+WW±W^+W^-W^\pm and ttˉW±W+WW±t \bar t W^\pm \rightarrow W^+W^-W^\pm yield a cross section of order 0.1 fb if there is no significant Higgs boson contribution. For a Higgs boson with mH2MZm_H^{} \simeq 2M_Z^{}, the triple massive-gauge-boson production rate could be enhanced by a factor of 464-6.Comment: RevTeX 3.0; 14 pages plus 7 figures; ps files available via anonymous ftp at ftp://ucdhep.ucdavis.edu/han/vvv/vvv.ps,fig*_vvv.p
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