1. |
- de Jong, R. S., et al.
(författare)
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4MOST : Project overview and information for the First Call for Proposals
- 2019
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Ingår i: The Messenger. - : European Southern Observatory. - 0722-6691. ; 175, s. 3-11
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- We introduce the 4-metre Multi-Object Spectroscopic Telescope (4MOST), a new high-multiplex, wide-field spectroscopic survey facility under development for the four-metre-class Visible and Infrared Survey Telescope for Astronomy (VISTA) at Paranal. Its key specifications are: a large field of view (FoV) of 4.2 square degrees and a high multiplex capability, with 1624 fibres feeding two low-resolution spectrographs (R = λ/Δλ ~ 6500), and 812 fibres transferring light to the high-resolution spectrograph (R ~ 20 000). After a description of the instrument and its expected performance, a short overview is given of its operational scheme and planned 4MOST Consortium science; these aspects are covered in more detail in other articles in this edition of The Messenger. Finally, the processes, schedules, and policies concerning the selection of ESO Community Surveys are presented, commencing with a singular opportunity to submit Letters of Intent for Public Surveys during the first five years of 4MOST operations.
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2. |
- Bijavara Seshashayana, Shilpa
(författare)
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Cosmic Origin of Fluorine : The Open Cluster Perspective
- 2024
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The study of open clusters enables the determination of accurate values for a multitude of variables, as the stars within them are expected to have a con sistent age, distance, and chemical content. Consequently, they are optimal for elucidating the cosmic genesis of complex elements, such as Fluorine. The objective of this project is to analyze the abundance of Fluorine in 13 open clusters, in which we have observed 31 stars in total. Additionally, eight field stars have been included in the analysis. This is the most exhaus tive and homogeneous database to date, which has been designed to derive Fluorine abundances across the galactic disk. While the principal objective is to comprehend the distribution of galactic Fluorine, the abundances of Cerium are also derived in order to elucidate the interrelationship between Fluorine and sprocess elements. In addition to the aforementioned elements, the abundances of Magnesium are derived in order to facilitate the categorization of the field stars in the low? and high? sequences, which is of importance for our method of determining stellar parameters. The abundances of Fluorine and Cerium are compared with metallicities, ages, and galactocentric distances in order to provide valuable insights into the origin of these elements through galactic chemical evolution models. The spectra were collected using the highresolution GIANOB instrument, which operates at the 3.58meter Galileo National Telescope in the near infrared wavelength range. The Python version of Spectroscopy Made Easy was employed to analyze the spectra and derive stellar parameters as well as abundances. The Hband region was used to derive stellar parameters. The stellar parameters were obtained by analyzing the OH, CN, and CO molecular lines and band heads in addition to Fe I lines. Kband HF lines (?? 2.28, 2.33 ?m), three Kband Mg I lines (?? 2.10, 2.11, 2.15 ?m), and two Hband Ce II lines (?? 1.66, and 1.71 ?m) were used to derive Fluorine, Magnesium, and Cerium abundances, respectively. When compared with theoretical models, the observed trends suggest that both asymptotic giant branch stars and massive stars—including a proportion of fast rotators that are likely to increase with declining metallicity—are necessary to explain the cosmic origin of Fluorine.
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3. |
- Hartman, Henrik, et al.
(författare)
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First storage of ion beams in the Double Electrostatic Ion-Ring Experiment : DESIREE
- 2013
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Ingår i: Review of Scientific Instruments. - : American Institute of Physics (AIP). - 0034-6748 .- 1089-7623. ; 84:5
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Tidskriftsartikel (refereegranskat)abstract
- We report on the first storage of ion beams in the Double ElectroStatic Ion Ring ExpEriment, DESIREE, at Stockholm University. We have produced beams of atomic carbon anions and small carbon anion molecules (Cn-, n = 1, 2, 3, 4) in a sputter ion source. The ion beams were accelerated to 10 keV kinetic energy and stored in an electrostatic ion storage ring enclosed in a vacuum chamber at 13 K. For 10 keV C2- molecular anions we measure the residual-gas limited beam storage lifetime to be 448 s +/- 18 s with two independent detector systems. Using the measured storage lifetimes we estimate that the residual gas pressure is in the 10-14 mbar range. When high current ion beams are injected, the number of stored particles does not follow a single exponential decay law as would be expected for stored particles lost solely due to electron detachment in collision with the residual-gas. Instead, we observe a faster initial decay rate, which we ascribe to the effect of the space charge of the ion beam on the storage capacity.
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4. |
- Hartman, Henrik, et al.
(författare)
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Negative ion relaxation and reactions in a cryogenic storage ring
- 2020
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Ingår i: Journal of Physics: Conference Series Vol 1412. - : IOP Publishing. - 1742-6588 .- 1742-6596.
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Konferensbidrag (refereegranskat)abstract
- An overview of recent experimental results of studies of negative atomic and molecular ions in the Double ElectroStatic Ion-Ring ExpEriment, DESIREE is given. Metastable level lifetimes in atomic negative ions have been measured by time-dependent laser photodetachment. Rotational relaxation of diatomic anions is studied by near-threshold photodetachment. Spontaneous decays of small metal cluster anions by electron emission and fragmentation is studied with decay-channel specificity. Finally, mutual neutralisation of pairs of negative and positive ions has been investigated with initial and final state selectivity.
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5. |
- Jönsson, Henrik, et al.
(författare)
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Abundances of disk and bulge giants from high-resolution optical spectra I. O, Mg, Ca, and Ti in the solar neighborhood and Kepler field samples
- 2017
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Ingår i: Astronomy and Astrophysics. - : EDP SCIENCES S A. - 0004-6361 .- 1432-0746. ; 598
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Tidskriftsartikel (refereegranskat)abstract
- Context. The Galactic bulge is an intriguing and significant part of our Galaxy, but it is hard to observe because it is both distant and covered by dust in the disk. Therefore, there are not many high-resolution optical spectra of bulge stars with large wavelength coverage, whose determined abundances can be compared with nearby, similarly analyzed stellar samples. Aims. We aim to determine the diagnostically important alpha elements of a sample of bulge giants using high-resolution optical spectra with large wavelength coverage. The abundances found are compared to similarly derived abundances from similar spectra of similar stars in the local thin and thick disks. In this first paper we focus on the solar neighborhood reference sample. Methods. We used spectral synthesis to derive the stellar parameters as well as the elemental abundances of both the local and bulge samples of giants. We took special care to benchmark our method of determining stellar parameters against independent measurements of effective temperatures from angular diameter measurements and surface gravities from asteroseismology. Results. In this first paper we present the method used to determine the stellar parameters and elemental abundances, evaluate them, and present the results for our local disk sample of 291 giants. Conclusions. When comparing our determined spectroscopic temperatures to those derived from angular diameter measurements, we reproduce these with a systematic difference of + 10 K and a standard deviation of 53 K. The spectroscopic gravities reproduce those determined from asteroseismology with a systematic off set of + 0.10 dex and a standard deviation of 0.12 dex. When it comes to the abundance trends, our sample of local disk giants closely follows trends found in other works analyzing solar neighborhood dwarfs, showing that the much brighter giant stars are as good abundance probes as the often used dwarfs.
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6. |
- Thorsbro, B., et al.
(författare)
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Evidence against Anomalous Compositions for Giants in the Galactic Nuclear Star Cluster
- 2018
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Ingår i: Astrophysical Journal. - : Bibliopolis, Edizioni di Filosofia e Scienze. - 0004-637X .- 1538-4357. ; 866:1
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Tidskriftsartikel (refereegranskat)abstract
- Very strong Sc I lines have recently been found in cool M giants in the Nuclear Star Cluster (NSC) in the Galactic center. Interpreting these as anomalously high scandium abundances in the Galactic center would imply a unique enhancement signature and chemical evolution history for NSCs, and a potential test for models of chemical enrichment in these objects. We present high resolution K-band spectra (NIRSPEC/Keck II) of cool M giants situated in the solar neighborhood and compare them with spectra of M giants in the NSC. We clearly identify strong Sc I lines in our solar neighborhood sample as well as in the NSC sample. The strong Sc I lines in M giants are therefore not unique to stars in the NSC and we argue that the strong lines are a property of the line formation process that currently escapes accurate theoretical modeling. We further conclude that for giant stars with effective temperatures below approximately 3800 K these Sc I lines should not be used for deriving the scandium abundances in any astrophysical environment until we better understand how these lines are formed. We also discuss the lines of vanadium, titanium, and yttrium identified in the spectra, which demonstrate a similar striking increase in strength below 3500 K effective temperature.
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7. |
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8. |
- Abdulla, Aree, et al.
(författare)
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Platelets regulate P-selectin expression and leukocyte rolling in inflamed venules of the pancreas
- 2012
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Ingår i: European Journal of Pharmacology. - : Elsevier BV. - 1879-0712 .- 0014-2999. ; 682:1-3, s. 153-160
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Tidskriftsartikel (refereegranskat)abstract
- Recent data suggest that platelets regulate inflammatory changes and tissue damage in acute pancreatitis although the role of platelets in leukocyte-endothelium interactions in the pancreatic microcirculation is not known. The aim of this study was to define the impact of platelets on leukocyte rolling and adhesion in acute pancreatitis. Acute pancreatitis was induced in C57BL/6 mice by caerulein challenge. Mice were treated with an a anti-GP1b alpha (CD42b) antibody, which depletes platelets, or a control antibody before caerulein. Leukocyte rolling and adhesion were determined by the use of intravital fluorescence microscopy 18 h after the last dose of caerulein. In separate experiments, leukocyte-endothelium interactions were determined before and after administration of an anti-P-selectin, anti-PSGL-1 and a control antibody in mice with caerulein pancreatitis. Circulating platelet-neutrophil aggregates and pancreatic P-selectin mRNA were quantified 1 and 6 h respectively after caerulein challenge. Caerulein administration increased leukocyte and platelet interactions in the pancreatic microvasculature, increased tissue damage and expression of P-selectin mRNA in the pancreas as well as platelet-neutrophil complexes in the circulation. Notably, platelet depletion markedly reduced caerulein-provoked leukocyte rolling and adhesion in postcapillary venules. Interestingly, depletion of platelets significantly decreased caerulein-induced gene expression of P-selectin in the pancreas. Moreover, immunoneutralization of P-selectin and PSGL-1 abolished leukocyte rolling in the pancreatic venules triggered by caerulein. Our novel findings demonstrate that platelets regulate leukocyte rolling in acute pancreatitis via induction of P-selectin, which was critical in supporting leukocyte rolling in inflamed venules of the pancreas. (C) 2012 Elsevier B.V. All rights reserved.
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9. |
- Abdulla, Aree, et al.
(författare)
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Role of platelets in experimental acute pancreatitis.
- 2011
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Ingår i: British Journal of Surgery. - : Oxford University Press (OUP). - 1365-2168 .- 0007-1323. ; 98, s. 93-103
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND:: Platelets not only control thrombosis and haemostasis but may also regulate inflammatory processes. Acute pancreatitis (AP) is characterized by changes in both coagulation and proinflammatory activities. The role of platelets in AP is not yet known. METHODS:: AP was induced in C57BL/6 mice by repeated caerulein administration (50 µg/kg intraperitoneally). Mice received a platelet-depleting or control antibody before caerulein challenge. Neutrophil infiltration, myeloperoxidase (MPO) and macrophage inflammatory protein (MIP) 2 levels, acinar cell necrosis and haemorrhage in the pancreas, as well as serum amylase activity, were determined 24 h after caerulein injection. In an alternative model of pancreatitis, L-arginine (4 g/kg intraperitoneally) was given twice with an interval of 1 h and tissue samples were taken after 72 h [Correction added after online publication 29 September 2010: in the preceding sentence, 4 mg/kg was corrected to 4 g/kg]. RESULTS:: Caerulein administration increased acinar cell necrosis, neutrophil infiltration, focal haemorrhage and serum amylase levels. Platelet depletion reduced acinar cell necrosis, haemorrhage and serum amylase levels in AP. Depletion of platelets decreased caerulein-induced MPO levels and neutrophil recruitment in the pancreas. Platelet depletion abolished caerulein-induced MIP-2 generation in the pancreas and circulation. The effects of platelet depletion on necrosis, neutrophils and MPO levels were confirmed in L-arginine-induced pancreatitis. CONCLUSION:: Platelets play a crucial role in AP by regulating neutrophil infiltration, most likely mediated by MIP-2 production in the pancreas. Copyright © 2010 British Journal of Surgery Society Ltd. Published by John Wiley & Sons, Ltd.
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10. |
- Alhuseinalkhudhur, Ali, et al.
(författare)
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Human Epidermal Growth Factor Receptor 2-Targeting [68Ga]Ga-ABY-025 PET/CT Predicts Early Metabolic Response in Metastatic Breast Cancer.
- 2023
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Ingår i: Journal of Nuclear Medicine. - : Society of Nuclear Medicine. - 0161-5505 .- 1535-5667. ; 64:9, s. 1364-1370
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Tidskriftsartikel (refereegranskat)abstract
- Imaging using the human epidermal growth factor receptor 2 (HER2)-binding tracer 68Ga-labeled ZHER2:2891-Cys-MMA-DOTA ([68Ga]Ga-ABY-025) was shown to reflect HER2 status determined by immunohistochemistry and in situ hybridization in metastatic breast cancer (MBC). This single-center open-label phase II study investigated how [68Ga]Ga-ABY-025 uptake corresponds to biopsy results and early treatment response in both primary breast cancer (PBC) planned for neoadjuvant chemotherapy and MBC. Methods: Forty patients with known positive HER2 status were included: 19 with PBC and 21 with MBC (median, 3 previous treatments). [68Ga]Ga-ABY-025 PET/CT, [18F]F-FDG PET/CT, and core-needle biopsies from targeted lesions were performed at baseline. [18F]F-FDG PET/CT was repeated after 2 cycles of therapy to calculate the directional change in tumor lesion glycolysis (Δ-TLG). The largest lesions (up to 5) were evaluated in all 3 scans per patient. SUVs from [68Ga]Ga-ABY-025 PET/CT were compared with the biopsied HER2 status and Δ-TLG by receiver operating characteristic analyses. Results: Trial biopsies were HER2-positive in 31 patients, HER2-negative in 6 patients, and borderline HER2-positive in 3 patients. The [68Ga]Ga-ABY-025 PET/CT cutoff SUVmax of 6.0 predicted a Δ-TLG lower than -25% with 86% sensitivity and 67% specificity in soft-tissue lesions (area under the curve, 0.74 [95% CI, 0.67-0.82]; P = 0.01). Compared with the HER2 status, this cutoff resulted in clinically relevant discordant findings in 12 of 40 patients. Metabolic response (Δ-TLG) was more pronounced in PBC (-71% [95% CI, -58% to -83%]; P < 0.0001) than in MBC (-27% [95% CI, -16% to -38%]; P < 0.0001), but [68Ga]Ga-ABY-025 SUVmax was similar in both with a mean SUVmax of 9.8 (95% CI, 6.3-13.3) and 13.9 (95% CI, 10.5-17.2), respectively (P = 0.10). In multivariate analysis, global Δ-TLG was positively associated with the number of previous treatments (P = 0.0004) and negatively associated with [68Ga]Ga-ABY-025 PET/CT SUVmax (P = 0.018) but not with HER2 status (P = 0.09). Conclusion: [68Ga]Ga-ABY-025 PET/CT predicted early metabolic response to HER2-targeted therapy in HER2-positive breast cancer. Metabolic response was attenuated in recurrent disease. [68Ga]Ga-ABY-025 PET/CT appears to provide an estimate of the HER2 expression required to induce tumor metabolic remission by targeted therapies and might be useful as an adjunct diagnostic tool.
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