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- Schael, S, et al.
(author)
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Precision electroweak measurements on the Z resonance
- 2006
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In: Physics Reports. - : Elsevier BV. - 0370-1573 .- 1873-6270. ; 427:5-6, s. 257-454
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Research review (peer-reviewed)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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| 3. |
- Raiteri, C. M., et al.
(author)
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WEBT and XMM-Newton observations of 3C 454.3 during the post-outburst phase - Detection of the little and big blue bumps
- 2007
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In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 473:3, s. 819-827
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Journal article (peer-reviewed)abstract
- Context. The quasar-type blazar 3C 454.3 was observed to undergo an unprecedented optical outburst in spring 2005, affecting the source brightness from the near-IR to the X-ray frequencies. This was first followed by a millimetric and then by a radio outburst, which peaked in February 2006. Aims. In this paper we report on follow-up observations to study the multiwavelength emission in the post-outburst phase. Methods. Radio, near-infrared, and optical monitoring was performed by the Whole Earth Blazar Telescope (WEBT) collaboration in the 2006-2007 observing season. XMM-Newton observations on July 2-3 and December 18-19, 2006 added information on the X-ray and UV states of the source. Results. The source was in a faint state. The radio flux at the higher frequencies showed a fast decreasing trend, which represents the tail of the big radio outburst. It was followed by a quiescent state, common at all radio frequencies. In contrast, moderate activity characterized the near-IR and optical light curves, with a progressive increase of the variability amplitude with increasing wavelength. We ascribe this redder-when-brighter behaviour to the presence of a ""little blue bump"" due to line emission from the broad line region, which is clearly visible in the source spectral energy distribution (SED) during faint states. Moreover, the data from the XMM- Newton Optical Monitor reveal a rise of the SED in the ultraviolet, suggesting the existence of a "" big blue bump"" due to thermal emission from the accretion disc. The X-ray spectra are well fitted with a power- law model with photoelectric absorption, possibly larger than the Galactic one. However, the comparison with previous X-ray observations would imply that the amount of absorbing matter is variable. Alternatively, the intrinsic X-ray spectrum presents a curvature, which may depend on the X-ray brightness. In this case, two scenarios are possible. i) There is no extra absorption, and the X-ray spectrum hardens at low energies, the hardening being more evident in bright states; ii) there is a constant amount of extra absorption, likely in the quasar environment, and the X-ray spectrum softens at low energies, at least in faint X-ray states. This softening might be the result of a flux contribution by the high-frequency tail of the big blue bump.
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| 5. |
- Fan, Y., et al.
(author)
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Mechanical preparation of nano titanium dioxide powder and its optical properties
- 2007
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In: Journal of the Chinese Ceramic Society. - 0454-5648. ; 35:7, s. 832-837
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Journal article (peer-reviewed)abstract
- mechanical preparation of the nano-sized particles of TiO2 powder by a stirred bead mill was investigated. The particle sizes of the ground products were determined by the acoustic particle sizer, the nitrogen gas adsorption method and a scanning electron microscopy. The diameter of the nano-sized particles, which were obtained after milling for 7 h, is about 50 nm and the specific surface area is up to 70 m2/g. The surface and structure of the samples have been investigated with X-ray diffraction. It is indicated that an intense comminution in the mill leads to a progressive loss in crystallinity of TiO2. The catalytic degradation of methyl orange in water was also studied by a photometer. The results show that the nano-sized particles of TiO2 powder prepared by milling possess photocatalysis effect and are capable of absorption of ultraviolet radiation
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| 9. |
- Yan, H, et al.
(author)
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Superior neovascularization and muscle regeneration in ischemic skeletal muscles following VEGF gene transfer by rAAV1 pseudotyped vectors
- 2005
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In: Biochemical and Biophysical Research Communications. - : Elsevier BV. - 1090-2104 .- 0006-291X. ; 336:1, s. 287-298
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Journal article (peer-reviewed)abstract
- Recombinant adeno-associated virus serotype 2 (rAAV2) vector has been widely employed for gene therapy. Recent progress suggests that the new serotypes of AAV showed a better performance than did AAV2 in normal tissues. Here, we evaluate the potential role of human vascular endothelial growth factor (VEGF) gene transfer using rAAV vector pseudotyped with serotype I capsid proteins (rAAV1) in the treatment of muscle ischemia. In ischemic skeletal muscles, the rAAV1-LacZ vector allowed higher level, broader distribution, and long-lasting gene expression compared with the rAAV2-LacZ vector. Muscle VEGF165 production following the rAAV1-VEGF165 vector injection was 5-10 times higher than that following the rAAV2-VEGF165 vector injection. VEGF165 production mediated by the rAAV1-VEGF165 vector stimulated a large set of neovascularization with relatively mature vascular structures and enhanced muscle regeneration in the ischemic skeletal muscles. Thus, the rAAV1-NEGF165 vector mediated gene transfer may be a therapeutic approach to peripheral vascular diseases.
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| 10. |
- Zhang, Juankun, et al.
(author)
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A Label Free Electrochemical Nanobiosensor Study
- 2009
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In: Analytical Letters. - : Taylor and Francis. - 0003-2719 .- 1532-236X. ; 42:17, s. 2905-2913
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Journal article (peer-reviewed)abstract
- Nano-porous silicon (PS) is an attractive material for incorporation into biosensors, because it has a large surface area combined with the ability to generate both optical and electrical signals. In this paper, we describe a label-free nanobiosensor for bovine serum albumin (BSA). Nano-porous silicon produced in our laboratory was functionalized prior to immobilization of anti-BSA antibody on the surface. Reaction with BSA in phosphate buffered saline (PBS) buffer resulted in an impedance change which was inversely proportional to the concentration of the analyte. The system PBS buffer/antigen-antibody/PS constitutes an electrolyte-insulator-semiconductor (EIS) structure, thus furnishing an impedance EIS nanobiosensor. The linear range of the sensor was 0-0.27mgmL-1 and the sensitivity was less than 10 mu g mL-1.
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