| 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. |
- Bouvier, J., et al.
(författare)
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The Gaia-ESO Survey: A lithium-rotation connection at 5 Myr?
- 2016
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 590
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Tidskriftsartikel (refereegranskat)abstract
- Context. The evolution of lithium abundance in cool dwarfs provides a unique probe of nonstandard processes in stellar evolution. Aims. We investigate the lithium content of young low-mass stars in the 5 Myr old, star forming region NGC 2264 and its relationship with rotation. Methods. We combine lithium equivalent width measurements (EW(Li)) from the Gaia-ESO Survey with the determination of rotational periods from the CSI 2264 survey. We only consider bona fide nonaccreting cluster members to minimize the uncertainties on EW(Li). Results. We report the existence of a relationship between lithium content and rotation in NGC 2264 at an age of 5 Myr. The Li-rotation connection is seen over a restricted temperature range (Teff = 3800-4400 K), where fast rotators are Li-rich compared to slow rotators. This correlation is similar to, albeit of lower amplitude than, the Li-rotation connection previously reported for K dwarfs in the 125 Myr old Pleiades cluster. We investigate whether the nonstandard pre-main-sequence models developed so far to explain the Pleiades results, which are based on episodic accretion, pre-main-sequence, core-envelope decoupling, and/or radius inflation due to enhanced magnetic activity, can account for early development of the Li-rotation connection. While radius inflation appears to be the most promising possibility, each of these models has issues. We therefore also discuss external causes that might operate during the first few Myr of pre-main-sequence evolution, such as planet engulfment and/or steady disk accretion, as possible candidates for the common origin for Li excess and fast rotation in young low-mass pre-main-sequence stars. Conclusions. The emergence of a connection between lithium content and rotation rate at such an early age as 5 Myr suggests a complex link between accretion processes, early angular momentum evolution, and possibly planet formation, which likely impacts early stellar evolution and has yet to be fully deciphered.
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| 3. |
- Usher, Christopher, et al.
(författare)
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Rubin Observatory LSST Stars Milky Way and Local Volume Star Clusters Roadmap
- 2023
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Ingår i: Publications of the Astronomical Society of the Pacific. - 0004-6280 .- 1538-3873. ; 135:1049
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Tidskriftsartikel (refereegranskat)abstract
- The Vera C. Rubin Observatory will undertake the Legacy Survey of Space and Time, providing an unprecedented, volume-limited catalog of star clusters in the Southern Sky, including Galactic and extragalactic star clusters. The Star Clusters subgroup of the Stars, Milky Way and Local Volume Working Group has identified key areas where Rubin Observatory will enable significant progress in star cluster research. This roadmap represents our science cases and preparation for studies of all kinds of star clusters from the Milky Way out to distances of tens of megaparsecs.
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| 4. |
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| 5. |
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| 6. |
- Gubinelli, F., et al.
(författare)
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Characterisation of functional deficits induced by AAV overexpression of alpha-synuclein in rats
- 2023
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Ingår i: Current Research in Neurobiology. - : Elsevier BV. - 2665-945X. ; 4
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Tidskriftsartikel (refereegranskat)abstract
- Background: In the last decades different preclinical animal models of Parkinson's disease (PD) have been generated, aiming to mimic the progressive neuronal loss of midbrain dopaminergic (DA) cells as well as motor and non-motor impairment. Among all the available models, AAV-based models of human alpha-synuclein (h-aSYN) overexpression are promising tools for investigation of disease progression and therapeutic interventions. Objectives: The goal with this work was to characterise the impairment in motor and non-motor domains following nigrostriatal overexpression of h-aSYN and correlate the behavioural deficits with histological assessment of associated pathology. Methods: Intranigral injection of an AAV9 expressing h-aSYN was compared with untreated animals, 6-OHDA and AAV9 expressing either no transgene or GFP. The animals were assessed on a series of simple and complex behavioural tasks probing motor and non-motor domains. Post-mortem neuropathology was analysed using immunohistochemical methods. Results: Overexpression of h-aSYN led to progressive degeneration of DA neurons of the SN and axonal terminals in the striatum (STR). We observed extensive nigral and striatal pathology, resembling that of human PD brain, as well as the development of stable progressive deficit in simple motor tasks and in non-motor domains such as deficits in motivation and lateralised neglect. Conclusions: In the present work we characterized a rat model of PD that closely resembles human PD pathology at the histological and behavioural level. The correlation of cell loss with behavioural performance enables the selection of rats which can be used in neuroprotective or neurorestorative therapies.
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| 7. |
- Gubinelli, F., et al.
(författare)
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Lateralized deficits after unilateral AAV-vector based overexpression of alpha-synuclein in the midbrain of rats on drug-free behavioral tests
- 2022
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Ingår i: Behavioural Brain Research. - : Elsevier BV. - 0166-4328. ; 429
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Tidskriftsartikel (refereegranskat)abstract
- Background: Preclinical rodent models of Parkinson's aim to recapitulate some of the hallmarks of the disease as it presents in humans, including the progressive neuronal loss of dopaminergic neurons in the midbrain as well as the development of a behavioral phenotype. AAV vector-based models of alpha-synuclein overexpression are a promising tool to achieve such animal models with high face and predictive validity. Objective: We have developed a preclinical rodent model of Parkinson's disease using an AAV-vector based overexpression of human alpha-synuclein. In the present work we characterize this model on a behavioral and histopathological level. Methods: We use a AAV9 vector for transgene delivery to overexpress human alpha-synuclein under a CBA promoter. We compare the behavioral and histopathological changes to a AAV vector control group where the transgene was omitted and to that of a 6-OHDA lesion control. We assessed the behavioral performance of these three groups on a series of tests (Cylinder, Stepping, Corridor) at baseline and up to 22 weeks post-injection at which point we performed electrochemical recordings of dopamine kinetics. Results: The overexpression of human alpha-synuclein led to the progressive manifestation of behavioral deficits on all three behavioral tests. This was accompanied with impaired dopamine release and reuptake kinetics as demonstrated by electrochemical detection methods. Histopathological quantifications corroborated the findings that we induced a moderate cell loss with remaining cells displaying pathological markers which are abundant in the brains of human PD patients. Conclusions: In the present work we developed a characterized a rat model of PD that closely mimics human disease development and pathology. Such model will be of great use for investigation of disease mechanisms and early therapeutic interventions.
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| 8. |
- Marleau, G.-D., et al.
(författare)
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Accreting protoplanets : Spectral signatures and magnitude of gas and dust extinction at H α
- 2022
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 657
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Tidskriftsartikel (refereegranskat)abstract
- Context. Accreting planetary-mass objects have been detected at H α, but targeted searches have mainly resulted in non-detections. Accretion tracers in the planetary-mass regime could originate from the shock itself, making them particularly susceptible to extinction by the accreting material. High-resolution (R > 50 000) spectrographs operating at H α should soon enable one to study how the incoming material shapes the line profile.Aims. We calculate how much the gas and dust accreting onto a planet reduce the H α flux from the shock at the planetary surface and how they affect the line shape. We also study the absorption-modified relationship between the H α luminosity and accretion rate.Methods. We computed the high-resolution radiative transfer of the H α line using a one-dimensional velocity–density–temperature structure for the inflowing matter in three representative accretion geometries: spherical symmetry, polar inflow, and magnetospheric accretion. For each, we explored the wide relevant ranges of the accretion rate and planet mass. We used detailed gas opacities and carefully estimated possible dust opacities.Results. At accretion rates of Ṁ ≲ 3 × 10−6 MJ yr−1, gas extinction is negligible for spherical or polar inflow and at most AH α ≲ 0.5 mag for magnetospheric accretion. Up to Ṁ ≈ 3 × 10−4 MJ yr−1, the gas contributes AH α ≲ 4 mag. This contribution decreases with mass. We estimate realistic dust opacities at H α to be κ ~ 0.01–10 cm2 g−1, which is 10–104 times lower than in the interstellar medium. Extinction flattens the LH α –Ṁ relationship, which becomes non-monotonic with a maximum luminosity LH α ~ 10−4 L⊙ towards Ṁ ≈ 10−4 MJ yr−1 for a planet mass ~10 MJ. In magnetospheric accretion, the gas can introduce features in the line profile, while the velocity gradient smears them out in other geometries.Conclusions. For a wide part of parameter space, extinction by the accreting matter should be negligible, simplifying the interpretation of observations, especially for planets in gaps. At high Ṁ, strong absorption reduces the H α flux, and some measurements can be interpreted as two Ṁ values. Highly resolved line profiles (R ~ 105) can provide (complex) constraints on the thermal and dynamical structure of the accretion flow.
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| 9. |
- Venuti Björkman, Jacob, et al.
(författare)
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Investigating the Effects of Organonitrogen Types on Hydrodearomatization Reactions over Commercial NiMoS Catalyst
- 2022
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Ingår i: Catalysts. - : MDPI AG. - 2073-4344. ; 12:7, s. 736-
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Tidskriftsartikel (refereegranskat)abstract
- The hydrogenation of polyaromatic compounds (PACs) present in mineral oils is of great importance when it comes to the desired product properties and the minimization of health hazards; however, the presence of organonitrogen inhibits the conversion of these compounds. In this study, the inhibition effects of different types of organonitrogen compounds (acridine (ACR) and carbazole (CBZ)-basic and nonbasic organonitrogen) on the hydrodearomatization (HDA) of phenanthrene over a sulfided commercial NiMo/Al2O3 catalyst were investigated in a microflow trickle-bed reactor at a temperature range of 280 to 320 degrees C and at a total pressure of 120 barg. Analysis of the experimental results shows that the hydrogenation of phenanthrene is significantly decreased in the presence of organonitrogen, with acridine showing stronger inhibiting effects. The extent of hydrodenitrogenation (HDN) is shown to correlate with the inhibition degree with a higher extent of HDN being achieved for carbazole than for acridine. Results from co-feeding different nitrogen types (acridine and carbazole) indicate that basic nitrogen is the dominating type of organonitrogen inhibitor. Recovery of catalyst activity in the absence of organonitrogen indicates fully reversible deactivation suggesting that inhibition relates to competitive adsorption and slower reaction rate of HDN compared to HDA.
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