| 1. |
- 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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| 2. |
- Shi, K. W., et al.
(författare)
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Observation of magnetic droplets in magnetic tunnel junctions
- 2022
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Ingår i: Science China-Physics Mechanics & Astronomy. - : Springer Science and Business Media LLC. - 1674-7348 .- 1869-1927. ; 65:2
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Tidskriftsartikel (refereegranskat)abstract
- Magnetic droplets, a class of highly nonlinear magnetodynamic solitons, can be nucleated and stabilized in nanocontact spin-torque nano-oscillators. Here we experimentally demonstrate magnetic droplets in magnetic tunnel junctions (MTJs). The droplet nucleation is accompanied by power enhancement compared with its ferromagnetic resonance modes. The nucleation and stabilization of droplets are ascribed to the double-CoFeB free-layer structure in the all-perpendicular MTJ, which provides a low Zhang-Li torque and a high pinning field. Our results enable better electrical sensitivity in fundamental studies of droplets and show that the droplets can be utilized in MTJ-based applications and materials science.
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| 3. |
- Cai, G. Q., et al.
(författare)
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Effects of habitat complexity on stochastic nonlinear ecosystems
- 2016
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Ingår i: International Journal of Dynamics and Control. - : Springer. - 2195-268X .- 2195-2698. ; 4:3, s. 275-283
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Tidskriftsartikel (refereegranskat)abstract
- The term “Habitat Complexity” is used to measure the coupling level between different species in an ecosystem. It plays an important role to an ecosystem in which two or more species are interacting with each other. In the present paper, effects of the habitat complexity on predator–prey ecosystems with or without noise disturbances are investigated. Stochastic analysis methods of the Ito differential equations, the stochastic averaging method, and the Monte Carlo simulation are applied to obtain the stationary probability densities of the predator and prey population densities. It is found that the effects of the habitat complexity on the system dynamical behaviors are quite different for the deterministic case and the stochastic case. In absence of the noises, there are two bifurcation points dividing the level of habitat complexity into three regions: weak, moderate and strong. In the three regions, limit cycles, co-existing equilibrium states, and predator-extinct equilibrium states are present, respectively. In the stochastic case, the stable invariant measures in terms of probability distributions replace both the limit cycles and coexisting equilibriums in the regions of weak and moderate habitat complexity. For the case of strong habitat complexity, although the predator remains extinct, the prey is not in an equilibrium state, but possesses a probability distribution.
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| 4. |
- Cai, Yangjian, et al.
(författare)
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Coincidence subwavelength fractional Fourier transform
- 2006
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Ingår i: Optical Society of America. Journal A. - 1084-7529 .- 1520-8532. ; 23:4, s. 835-841
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Tidskriftsartikel (refereegranskat)abstract
- The coincidence subwavelength fractional Fourier transforms (FRTs) with entangled photon pairs and incoherent light radiation are introduced as an extension of the recently introduced coincidence FRT. Optical systems for implementing the coincidence subwavelength FRTs are designed. The width of the coincidence subwavelength FRT pattern is two times narrower than the width of the coincidence FRT. The coincidence subwavelength FRT with partially coherent light radiation is also studied numerically. Differences between the coincidence subwavelength FRT with entangled photon pairs and that with incoherent light radiation are discussed.
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| 5. |
- Qian, J., et al.
(författare)
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Quantum-Dots-Doped ORMOSIL Nanoparticles as Optical Probes for Total Internal Reflection Fluorescence Imaging of Cancer Cells
- 2009
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Ingår i: IEEE Journal of Selected Topics in Quantum Electronics. - : Institute of Electrical and Electronics Engineers (IEEE). - 1077-260X .- 1558-4542. ; 15:5, s. 1374-1379
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Tidskriftsartikel (refereegranskat)abstract
- We report the novel use of organically modified silica (ORMOSIL) nanoparticles to encapsulate hydrophobic quantum dots (QDs), thus making them hydrophilic and yet maintaining stable optical properties. QDs are resistant to photobleaching, and the cationic charge on the surfaces of the ORMOSIL nanoparticles can facilitate them being uptaken at the cell substrate regions. An objective-lens-based total internal reflection fluorescence (TIRF) microscope is used to observe the staining and dynamics of HeLa cancer cells, which have been targeted by the synthesized QD-doped ORMOSIL nanoparticles. Since the same microscope objective is used for launching the incident light beam and the collection lens, the observation and manipulation of live samples under a TIRF microscope is therefore much easier than that in the case of using the conventional prism-based TIRF setup. The present nanoparticle-assisted approach has made TIRF imaging a much more powerful tool for real-time monitoring of intracellular biological metabolic activities.
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| 6. |
- Wei, M., et al.
(författare)
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Differential absorption optical coherence tomography with strong absorption contrast agents of gold nanorods
- 2009
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Ingår i: Frontiers of Optoelectronics in China. - : Springer Science and Business Media LLC. - 1674-4128 .- 1674-4594. ; 2:2, s. 141-145
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Tidskriftsartikel (refereegranskat)abstract
- Plasmon-resonant gold nanorods (GNRs) are demonstrated as strong absorption contrast agents for optical coherence tomography (OCT). OCT imaging of tissue phantoms doped with GNRs of different resonant wavelengths and concentrations is studied. To utilize the high absorption property of GNRs, a differential absorption OCT imaging is introduced to retrieve the absorption information of GNRs from conventional backscattered signals. It is shown that the contrast of the OCT image can be enhanced significantly when the plasmon resonant wavelength of the GNRs matches the central wavelength of the OCT source.
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| 7. |
- Zhang, H. L., et al.
(författare)
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Solid solution strengthening of high-entropy alloys from first-principles study
- 2022
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Ingår i: Journal of Materials Science & Technology. - : Elsevier BV. - 1005-0302. ; 121, s. 105-116
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Tidskriftsartikel (refereegranskat)abstract
- Solid solution strengthening (SSS) is one kind of strengthening mechanisms and plays an important role in alloy design, in particular for single-phase alloys including high-entropy alloys (HEAs). The classical Labusch-Nabarro model and its expansions are most widely applicable to treating SSS of solid solution alloys including both conventional alloys (CAs) and HEAs. In this study, the SSS effects in a series of Fe based CAs and HEAs are investigated by using the classical Labusch-Nabarro model and its expansions. The size misfit and shear modulus misfit parameters are derived from first-principles calculations. Based on available experimental data in combination with empirical SSS model, we propose fitting constants (i.e., the ratio between experimental hardness and predicted SSS effect) for these two families of alloys. The predicted host/alloy family-dependent fitting constants can be used to estimate the hardness of these SSS alloys. General agreement between predicted and measured hardness values is satisfactory for both CAs and HEAs, implying that the proposed approach is reliable and successful.
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