| 1. |
- Schael, S., et al.
(författare)
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Electroweak measurements in electron positron collisions at W-boson-pair energies at LEP
- 2013
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Ingår i: Physics Reports. - : Elsevier BV. - 0370-1573 .- 1873-6270. ; 532:4, s. 119-244
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Forskningsöversikt (refereegranskat)abstract
- Electroweak measurements performed with data taken at the electron positron collider LEP at CERN from 1995 to 2000 are reported. The combined data set considered in this report corresponds to a total luminosity of about 3 fb(-1) collected by the four LEP experiments ALEPH, DELPHI, 13 and OPAL, at centre-of-mass energies ranging from 130 GeV to 209 GeV. Combining the published results of the four LEP experiments, the measurements include total and differential cross-sections in photon-pair, fermion-pair and four-fermion production, the latter resulting from both double-resonant WW and ZZ production as well as singly resonant production. Total and differential cross-sections are measured precisely, providing a stringent test of the Standard Model at centre-of-mass energies never explored before in electron positron collisions. Final-state interaction effects in four-fermion production, such as those arising from colour reconnection and Bose Einstein correlations between the two W decay systems arising in WW production, are searched for and upper limits on the strength of possible effects are obtained. The data are used to determine fundamental properties of the W boson and the electroweak theory. Among others, the mass and width of the W boson, m(w) and Gamma(w), the branching fraction of W decays to hadrons, B(W -> had), and the trilinear gauge-boson self-couplings g(1)(Z), K-gamma and lambda(gamma), are determined to be: m(w) = 80.376 +/- 0.033 GeV Gamma(w) = 2.195 +/- 0.083 GeV B(W -> had) = 67.41 +/- 0.27% g(1)(Z) = 0.984(-0.020)(+0.018) K-gamma - 0.982 +/- 0.042 lambda(gamma) = 0.022 +/- 0.019. (C) 2013 Elsevier B.V. All rights reserved.
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| 2. |
- Schael, S, et al.
(författare)
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Precision electroweak measurements on the Z resonance
- 2006
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Ingår i: Physics Reports. - : Elsevier BV. - 0370-1573 .- 1873-6270. ; 427:5-6, s. 257-454
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Forskningsöversikt (refereegranskat)abstract
- We report on the final electroweak measurements performed with data taken at the Z resonance by the experiments operating at the electron-positron colliders SLC and LEP. The data consist of 17 million Z decays accumulated by the ALEPH, DELPHI, L3 and OPAL experiments at LEP, and 600 thousand Z decays by the SLID experiment using a polarised beam at SLC. The measurements include cross-sections, forward-backward asymmetries and polarised asymmetries. The mass and width of the Z boson, m(Z) and Gamma(Z), and its couplings to fermions, for example the p parameter and the effective electroweak mixing angle for leptons, are precisely measured: m(Z) = 91.1875 +/- 0.0021 GeV, Gamma(Z) = 2.4952 +/- 0.0023 GeV, rho(l) = 1.0050 +/- 0.0010, sin(2)theta(eff)(lept) = 0.23153 +/- 0.00016. The number of light neutrino species is determined to be 2.9840 +/- 0.0082, in agreement with the three observed generations of fundamental fermions. The results are compared to the predictions of the Standard Model (SM). At the Z-pole, electroweak radiative corrections beyond the running of the QED and QCD coupling constants are observed with a significance of five standard deviations, and in agreement with the Standard Model. Of the many Z-pole measurements, the forward-backward asymmetry in b-quark production shows the largest difference with respect to its SM expectation, at the level of 2.8 standard deviations. Through radiative corrections evaluated in the framework of the Standard Model, the Z-pole data are also used to predict the mass of the top quark, m(t) = 173(+10)(+13) GeV, and the mass of the W boson, m(W) = 80.363 +/- 0.032 GeV. These indirect constraints are compared to the direct measurements, providing a stringent test of the SM. Using in addition the direct measurements of m(t) and m(W), the mass of the as yet unobserved SM Higgs boson is predicted with a relative uncertainty of about 50% and found to be less than 285 GeV at 95% confidence level. (c) 2006 Elsevier B.V. All rights reserved.
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| 4. |
- Bernal, Ximena E., et al.
(författare)
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Empowering Latina scientists
- 2019
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 363:6429, s. 825-826
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 11. |
- Beal, Jacob, et al.
(författare)
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Robust estimation of bacterial cell count from optical density
- 2020
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Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data.
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| 18. |
- Requies, J., et al.
(författare)
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Palladium-manganese catalysts supported on monolith systems for methane combustion
- 2008
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Ingår i: Applied Catalysis B. - : Elsevier BV. - 0926-3373 .- 1873-3883. ; 79:2, s. 122-131
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Tidskriftsartikel (refereegranskat)abstract
- Alumina-supported bimetallic and monometallic Mn and Pd monolithic catalysts were prepared and tested in methane combustion. Two different reactor configurations were adopted for catalyst testing, i.e. a fixed-bed laboratory-scale reactor and a pilot-plant reactor which allowed work at different temperatures and pressures. The results of catalyst performance showed that all bimetallic catalysts are considerably more stable for methane combustion than the monometallic palladium catalyst. With the aim to explain the relationship between activity-stability and structure and surface properties, the catalysts were characterized by TPO, XRD, XPS and ICP-AES. The high stability displayed by the bimetallic systems is attributed to the influence of manganese in retarding the decomposition of PdO into metallic palladium. Thus, it appears that manganese oxides inhibit PdO decomposition, as a consequence of the increase in oxygen mobility in the manganese oxide spinel phase.
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| 19. |
- Agrell, J., et al.
(författare)
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Production of hydrogen from methanol over Cu/ZnO catalysts promoted by ZrO2 and Al2O3
- 2003
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Ingår i: Journal of Catalysis. - : Elsevier BV. - 0021-9517 .- 1090-2694. ; 219:2, s. 389-403
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Tidskriftsartikel (refereegranskat)abstract
- Production of H-2 from methanol by steam reforming, partial oxidation, or a combination thereof was studied over Cu/ZnO-based catalysts. The catalysts were characterized by a variety of techniques, including N2O chemisorption, X-ray photoelectron spectroscopy, X-ray diffraction, and temperature-programmed reduction/oxidation. The influence of feed composition, reaction temperature, and catalyst formulation on H-2 production rate, product distribution, and catalyst lifetime was investigated. Distinct differences between the processes were observed with respect to catalyst behavior. ZrO2-containing catalysts, especially Cu/ZnO/ZrO2/Al2O3, exhibit the best performance in the steam reforming reaction. During partial oxidation, however, a binary Cu/ZnO catalyst exhibits the lowest light-off temperature and the lowest level of CO by-product. The redox properties of the catalyst appear to play a key role in determining the pathway for H-2 production. In particular. the extent of methanol and/or H-2 combustion at differential O-2 conversion is strongly dependent on the ease of copper oxidation in the catalyst.
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| 20. |
- Christou, S.Y, et al.
(författare)
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Reactivation of an Aged Commercial Three-Way Catalyst by Oxalic and Citric Acid Washing
- 2006
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 40, s. 2030-2036
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Tidskriftsartikel (refereegranskat)abstract
- The efficiency of dilute oxalic and citric acid solutions on improving the oxygen storage capacity (OSC) and catalytic activity of a severely aged (83 000 km) commercial three-way catalyst (TWC) has been investigated. Washing procedures applied after optimization of experimental parameters, namely, temperature, flow-rate, and concentration of acid solution, led to significant improvements of OSC and catalytic activity (based on dynamometer test measurements) of the aged TWC. The latter was made possible due to the removal of significant amounts of various contaminants accumulated on the catalyst surface (e.g., P, S, Pb, Ca, Zn, Si, Fe, Cu, and Ni) during driving conditions, as revealed by Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES) and X-ray Photoelectron Spectroscopy (XPS) analyses. For the first time, it is demonstrated that dilute oxalic acid solution significantly improves the catalytic activity of an aged commercial TWC toward CO, CxHy, and NOx conversions under real exhaust gas conditions (dynamometer tests) by two to eight times in the 250-450 degrees C range and the OSC quantity by up to 50%. Oxalic acid appears to be more efficient than citric acid in removing specifically P- and S-containing compounds from the catalyst surface, whereas citric acid in removing Pb- and Zn-containing compounds, thus uncovering surface active catalytic sites.
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| 22. |
- Ojeda, M., et al.
(författare)
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Synthesis of Rh nano-particles by the microemulsion technology - Particle size effect on the CO+H-2 reaction
- 2004
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Ingår i: Applied Catalysis A. - : Elsevier BV. - 0926-860X .- 1873-3875. ; 274:1-2, s. 33-41
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Tidskriftsartikel (refereegranskat)abstract
- Several alumina-supported rhodium-based catalysts have been prepared using the microemulsion technology. The change of microemulsion properties led to catalysts with different Rh particle size and narrow size distribution while keeping the same metal loading. The metal particle size was determined by XRD and TEM. These catalysts were tested in the CO hydrogenation reaction in order to investigate the influence of the Rh particle size. The catalytic results indicated that turnover frequency (TOF) increased about four times when the Rh particle size increased approximately from
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| 23. |
- Rojas, S., et al.
(författare)
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Preparation of carbon supported Pt and PtRu nanoparticles from microemulsion - Electrocatalysts for fuel cell applications
- 2005
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Ingår i: Applied Catalysis A. - : Elsevier BV. - 0926-860X .- 1873-3875. ; 285:02-jan, s. 24-35
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Tidskriftsartikel (refereegranskat)abstract
- A series of platinum and platinum ruthenium carbon supported electrocatalyst have been prepared by the microemulsion technique. The influence of parameters such as the preparation route, the metal loading and the PtRu stoichiometry on the morphology of the final nanoparticles has been studied. Irrespective the total metal loading, nanosized particles, displaying a narrow size distribution were obtained. In addition, particle size was found to be independent of the metal loading. Structural characteristics of these systems have been studied by XPS, X-ray diffraction, TEM, and TPR-TPO and their textural parameters by N-2 adsorption. The catalytic performance of the samples was evaluated in the electrochemical oxidation of methanol. The influence of the morphology on the catalytic performance of the catalysts is discussed in terms of their synthesis route. © 2005 Elsevier B.V. All rights reserved.
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| 24. |
- Van, T. L., et al.
(författare)
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Simultaneous discovery of cancer subtypes and subtype features by molecular data integration
- 2016
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Ingår i: Bioinformatics. - Oxford : Oxford University Press (OUP). - 1367-4803 .- 1367-4811. ; 32:17, s. 445-454
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Tidskriftsartikel (refereegranskat)abstract
- Motivation: Subtyping cancer is key to an improved and more personalized prognosis/treatment. The increasing availability of tumor related molecular data provides the opportunity to identify molecular subtypes in a data-driven way. Molecular subtypes are defined as groups of samples that have a similar molecular mechanism at the origin of the carcinogenesis. The molecular mechanisms are reflected by subtype-specific mutational and expression features. Data-driven subtyping is a complex problem as subtyping and identifying the molecular mechanisms that drive carcinogenesis are confounded problems. Many current integrative subtyping methods use global mutational and/or expression tumor profiles to group tumor samples in subtypes but do not explicitly extract the subtype-specific features. We therefore present a method that solves both tasks of subtyping and identification of subtype-specific features simultaneously. Hereto our method integrates' mutational and expression data while taking into account the clonal properties of carcinogenesis. Key to our method is a formalization of the problem as a rank matrix factorization of ranked data that approaches the subtyping problem as multi-view bi-clustering. Results: We introduce a novel integrative framework to identify subtypes by combining mutational and expression features. The incomparable measurement data is integrated by transformation into ranked data and subtypes are defined as multi-view bi-clusters. We formalize the model using rank matrix factorization, resulting in the SRF algorithm. Experiments on simulated data and the TCGA breast cancer data demonstrate that SRF is able to capture subtle differences that existing methods may miss.
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