| 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. |
- Bale, S. D., et al.
(författare)
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The FIELDS Instrument Suite for Solar Probe Plus
- 2016
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Ingår i: Space Science Reviews. - : Springer Science and Business Media LLC. - 0038-6308 .- 1572-9672. ; 204:1-4, s. 49-82
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Forskningsöversikt (refereegranskat)abstract
- NASA's Solar Probe Plus (SPP) mission will make the first in situ measurements of the solar corona and the birthplace of the solar wind. The FIELDS instrument suite on SPP will make direct measurements of electric and magnetic fields, the properties of in situ plasma waves, electron density and temperature profiles, and interplanetary radio emissions, amongst other things. Here, we describe the scientific objectives targeted by the SPP/FIELDS instrument, the instrument design itself, and the instrument concept of operations and planned data products.
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| 3. |
- Karlsson, Tomas, et al.
(författare)
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Quiet, Discrete Auroral Arcs-Observations
- 2020
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Ingår i: Space Science Reviews. - : Springer. - 0038-6308 .- 1572-9672. ; 216:1
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Forskningsöversikt (refereegranskat)abstract
- Quiet, discrete auroral arcs are an important and fundamental consequence of solar wind-magnetosphere interaction. We summarize the current standing of observations of such auroral arcs. We review the basic characteristics of the arcs, including occurrence in time and space, lifetimes, width and length, as well as brightness, and the energy of the magnetospheric electrons responsible for the optical emission. We briefly discuss the connection between single and multiple discrete arcs. The acceleration of the magnetospheric electrons by high-altitude electric potential structure is reviewed, together with our current knowledge of these structures. Observations relating to the potential drop, altitude distribution and lifetimes are reviewed, as well as direct evidence for the parallel electric fields of the acceleration structures. The current closure in the ionosphere of the currents carried by the auroral electrons is discussed together with its impact on the ionosphere and thermosphere. The connection of auroral arcs to the magnetosphere and generator regions is briefly touched upon. Finally we discuss how to progress from the current observational status to further our understanding of auroral arcs.
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| 4. |
- Lynch, A., et al.
(författare)
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Face indexing and shape analysis of salicylamide crystals grown in different solvents
- 2019
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Ingår i: CrystEngComm. - : Royal Society of Chemistry. - 1466-8033. ; 21:16, s. 2648-2659
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Tidskriftsartikel (refereegranskat)abstract
- The effect of solvent on salicylamide's crystal habit was investigated. Crystals grown experimentally in acetone, acetonitrile and methanol matched the attachment energy predicted rectangle plate vacuum habit. However, in ethyl acetate irregular hexagonal plate crystals form. This change in habit was found to be caused by the stunted growth of specific crystal faces during the crystallisation process. Single crystal and powder X-ray diffraction was carried out to rule out the possibility of a new polymorph. Given no new polymorphs were discovered, the changing habit makes face indexing of experimentally grown crystals difficult. A combination of experimental and modelling prediction tools was employed for the face indexing process. The interfacial angle between faces combined with preferred orientation P-XRD was found to be the most accurate and reliable method leading to successful identification of each salicylamide crystal face. The surface chemistry of each face was examined on a molecular level with insights into the possible growth attachment sites being made. It is deduced that ethyl acetate is adsorbed more strongly on the faces, the increased size of which, can explain the shape change.
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| 5. |
- Malkiewicz, Katarzyna, et al.
(författare)
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Nanomaterials in reach
- 2011
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Rapport (övrigt vetenskapligt/konstnärligt)
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| 6. |
- Malkiewicz, Katarzyna, et al.
(författare)
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Nanomaterials in reach
- 2011
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Ingår i: Toxicology Letters. - : Elsevier BV. - 0378-4274 .- 1879-3169. ; 205, s. S45-S45
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Several critical differences between the “nano” forms of substances and their “bulk” counterparts may necessitate additional considerations in regulatory frameworks to adequately address potential risks posed by nanomaterials (NMs). The aim of this presentation is to address the problematics of assessing and managing risks of NMs by the means of EU chemicals regulation REACH (Registration, Evaluation, and Authorization of Chemicals). It is based on the results of the SKEP-ERA net project “Nanomaterials in REACH”, which during year 2010 gathered international expertise on chemicals regulation, physico-chemical properties and toxicity of NMs, and environmental and technology policy. Analysis and discussion points cover following topics: definitions concerning nanomaterials, REACH provisions for registration of NMs as substances, and in articles (including “phase-in”/“non-phase-in” status, mass based tonnage thresholds, “prioritization” criteria, classification as hazardous, percentage thresholds in articles), substance identification, scope of data requirements, standardization and methodology for human and environmental hazards identification and risk characterisation. Examples of resulting recommendations include: (1) adopt a single overarching definition of NMs for regulatory purposes; (2) treat “nano” forms as different from their “bulk” counterparts and as “non-phase in” substances; (3) differentiate “nano” forms with the same core chemistry using differences in the physicochemical parameters; (4) introduce mandatory list of physicochemical properties for substance identification; (5) introduce alternatives to the tonnage triggers; (6) develop register of comprehensive information on the presence of NMs in articles; (7) extend a scope of data requirements with nano-specific data requirements; (8) develop nano-specific criteria for inclusion in the SVHC list.
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| 7. |
- Mella, M. R., et al.
(författare)
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Sounding rocket study of two sequential auroral poleward boundary intensifications
- 2011
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Ingår i: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 116, s. A00K18-
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Tidskriftsartikel (refereegranskat)abstract
- The Cascades-2 sounding rocket was launched on 20 March 2009 at 11: 04: 00 UT from the Poker Flat Research Range in Alaska, and flew across a series of poleward boundary intensifications (PBIs). The rocket initially crosses a diffuse arc, then crosses the equatorward extent of one PBI (a streamer), and finally crosses the initiation of a separate PBI before entering the polar cap. Each of the crossings have fundamentally different in situ electron energy and pitch angle structure, and different ground optics images of visible aurora. It is found that the diffuse arc has a quasi-static acceleration mechanism, and the intensification at the poleward boundary has an Alfvenic acceleration mechanism. The streamer shows characteristics of both types of acceleration. PFISR data provide ionospheric context for the rocket observations. Three THEMIS satellites in close conjunction with the rocket foot point show earthward flows and slight dipolarizations in the magnetotail associated with the in situ observations of PBI activity. An important goal of the Cascades-2 study is to bring together the different observational communities (rocket, ground cameras, ground radar, satellite) with the same case study. The Cascades-2 experiment is the first sounding rocket observation of a PBI sequence, enabling a detailed investigation of the electron signatures and optical aurora associated with various stages of a PBI sequence as it evolves from an Alfvenic to a more quasi-static structure.
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| 8. |
- Milligan, M., et al.
(författare)
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Market designs for high levels of variable generation
- 2014
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Ingår i: IEEE Power and Energy Society General Meeting.
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Konferensbidrag (refereegranskat)abstract
- Variable renewable generation is increasing in penetration in modern power systems, leading to higher variability in the supply and price of electricity as well as lower average spot prices. This raises new challenges, particularly in ensuring sufficient capacity and flexibility from conventional technologies. As the fixed costs and lifetimes of electricity generation investments are significant, designing markets and regulations which ensure efficient integration of renewable generation is a significant challenge. This panel presentation reviews the state of play in the USA and Europe with regard to these issues and considers new developments in both regions.
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| 9. |
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