| 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. |
- Anderson, Orlagh, et al.
(författare)
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An investigation of the antileishmanial properties of semi-synthetic saponins
- 2020
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Ingår i: RSC MEDICINAL CHEMISTRY. - : Royal Society of Chemistry (RSC). - 2632-8682. ; 11:7, s. 833-842
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Tidskriftsartikel (refereegranskat)abstract
- Leishmaniasis is a neglected tropical disease caused by insect-vector borne protozoan parasites of the,Leishmania species. Whilst infection threatens and affects millions of the global poor, vaccines are absent and drug therapy limited. Extensive efforts have recently been made to discover new leads from small molecule synthetic compound libraries held by industry; however, the number of new chemical entities identified and entering development as anti-leishmanials has been very low. This has led to increased interest in the possibility of discovering naturally derived compounds with potent antileishmanial activity which may be developed towards clinical applications. Plant-derived triterpenoid and steroidal saponins have long been considered as anti-microbials and here we describe an investigation of a library of 137 natural (9) and semi-synthetic saponins (128) for activity againstLeishmania mexicana, a causative agent of cutaneous leishmaniasis. The triterpenoid sapogenin, hederagenin, readily obtained in large quantities fromHedera helix(common ivy), was converted into a range of 128 derivatives. These semi-synthetic compounds, as well as saponins isolated from ivy, were examined with a phenotypic screening approach to identify potent and selective anti-leishmanial hits. This led to the identification of 12 compounds, including the natural saponin gypsogenin, demonstrating high potency (ED50< 10.5 mu M) against axenicL. mexicanaamastigotes, the mammalian pathogenic form. One of these, hederagenin disuccinate, was sufficiently non-toxic to the macrophage host cell to facilitate further analyses, selectivity index (SI) > 10. Whilst this was not active in an infected cell model, the anti-leishmanial properties of hederagenin-derivatives have been demonstrated, and the possibility of improving the selectivity of natural hederagenin through chemical modification has been established.
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| 3. |
- Romell, Jenny, et al.
(författare)
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Laboratory phase-contrast nanotomography of unstained Bombus terrestris compound eyes
- 2021
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Ingår i: Journal of Microscopy. - : Wiley. - 0022-2720 .- 1365-2818. ; 283:1, s. 29-40
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Tidskriftsartikel (refereegranskat)abstract
- Imaging the visual systems of bumblebees and other pollinating insects may increase understanding of their dependence on specific habitats and how they will be affected by climate change. Current high-resolution imaging methods are either limited to two dimensions (light- and electron microscopy) or have limited access (synchrotron radiation x-ray tomography). For x-ray imaging, heavy metal stains are often used to increase contrast. Here, we present micron-resolution imaging of compound eyes of buff-tailed bumblebees (Bombus terrestris) using a table-top x-ray nanotomography (nano-CT) system. By propagation-based phase-contrast imaging, the use of stains was avoided and the microanatomy could more accurately be reconstructed than in samples stained with phosphotungstic acid or osmium tetroxide. The findings in the nano-CT images of the compound eye were confirmed by comparisons with light- and transmission electron microscopy of the same sample and finally, comparisons to synchrotron radiation tomography as well as to a commercial micro-CT system were done.
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