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- Auffray, C., et al.
(författare)
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COVID-19 and beyond : a call for action and audacious solidarity to all the citizens and nations, it is humanity’s fight
- 2020
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Ingår i: F1000 Research. - : F1000 Research Ltd. - 2046-1402. ; 9, s. 1130-18
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Tidskriftsartikel (refereegranskat)abstract
- Background: Severe acute respiratory syndrome coronavirus 2 (SARSCoV-2) belongs to a subgroup of coronaviruses rampant in bats for centuries. It caused the coronavirus disease 2019 (COVID-19) pandemic. Most patients recover, but a minority of severe cases experience acute respiratory distress or an inflammatory storm devastating many organs that can lead to patient death. The spread of SARS-CoV-2 was facilitated by the increasing intensity of air travel, urban congestion and human contact during the past decades. Until therapies and vaccines are available, tests for virus exposure, confinement and distancing measures have helped curb the pandemic. Vision: The COVID-19 pandemic calls for safeguards and remediation measures through a systemic response. Self-organizing initiatives by scientists and citizens are developing an advanced collective intelligence response to the coronavirus crisis. Their integration forms Olympiads of Solidarity and Health. Their ability to optimize our response to COVID-19 could serve as a model to trigger a global metamorphosis of our societies with far-reaching consequences for attacking fundamental challenges facing humanity in the 21st century. Mission: For COVID-19 and these other challenges, there is no alternative but action. Meeting in Paris in 2003, we set out to "rethink research to understand life and improve health." We have formed an international coalition of academia and industry ecosystems taking a systems medicine approach to understanding COVID-19 by thoroughly characterizing viruses, patients and populations during the pandemic, using openly shared tools. All results will be publicly available with no initial claims for intellectual property rights. This World Alliance for Health and Wellbeing will catalyze the creation of medical and health products such as diagnostic tests, drugs and vaccines that become common goods accessible to all, while seeking further alliances with civil society to bridge with socio-ecological and technological approaches that characterise urban systems, for a collective response to future health emergencies.
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- Lorenz, D., et al.
(författare)
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Long-period variables in NGC 147 and NGC 185
- 2011
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 532
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Tidskriftsartikel (refereegranskat)abstract
- Context. Previous studies on the stellar content of the two nearby dwarf galaxies NGC 147 and NGC 185 reveal a rich population of late-type giants in both systems, including a large number of carbon-rich objects. These stars are known to show pronounced photometric variability, which can be used for a more detailed characterisation of these highly evolved stars. Owing to their well-studied parameters, these Local Group members are ideal candidates for comparative studies. Aims. Through photometric monitoring, we attempt to provide a catalogue of long-period variables (LPVs), including Mira variables, semi-regular variables, and even irregular variables in NGC 147 and NGC 185. We investigate the light variations and compare the characteristics of these two LPV populations with the results found for other galaxies, such as the LMC. Methods. We carried out time-series photometry in the i-band of the two target galaxies with the Nordic Optical Telescope (NOT), covering a time span of approximate to 2.5 years. More than 30 epochs were available for a period search. These data were then combined with single-epoch K-band photometry, also obtained with the NOT. Narrow-band photometry data from the literature was used to distinguish between O-rich and C-rich stars. Results. We report the detection of 513 LPVs in NGC 185 and 213 LPVs in NGC 147, showing amplitudes Delta i of up to approximate to 2(mag) and periods ranging between 90 and 800 days. The period-luminosity diagram for each of our target galaxies exhibits a well populated sequence of fundamental mode pulsators. The resulting period-luminosity relations we obtained are compared to relations from the literature. We discuss the universality of those relations because of which, as a side result, a correction of the distance modulus of NGC 185 may be necessary. A value of (m - M) = 24.(m)30 seems to be more appropriate to match the observed data. Only one of our two galaxies, namely NGC 185, has a significant fraction of possibly first overtone pulsators. An interpretation of this finding in terms of differences in the star-formation histories is suggested.
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| 10. |
- Lorenz, D., et al.
(författare)
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LPVs as possible distance indicators in NGC147 and NGC185
- 2012
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Ingår i: Astrophysics and Space Science Proceedings. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 1570-6591 .- 1570-6605. - 9783642220173 ; , s. 169-172
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Konferensbidrag (refereegranskat)abstract
- NGC147 and NGC185 are both dwarf galaxies and companions of the M31 Galaxy. These satellites of Andromeda show similar properties in their color magnitude diagram but also striking differences concerning their stellar content of intermediate age stars as well as their amount of gas and dust. This and the fact that their small apparent separation on the sky of approximately one degree make them very interesting for comparative studies. Photometric monitoring of stars in the i-band of the two dwarf galaxies NGC147 and NGC185 covering ≈ 2.5 years resulted in the discovery of a large number of Long Period Variables (LPVs). A total of 323 LPVs in NGC 185 and 147 LPVs in NGC147 were available for further analysis. Additional single-epoch Ks-band photometry was obtained in order to compare the resulting period luminosity diagrams with those of other systems like, e.g., the Large Magellanic Cloud (LMC). Making use of narrow-band photometry a significant fraction of the detected LPVs could be identified as carbonrich. To establish a universal relation between period and luminosity for LPVs, such variables need to be studied in different galaxies. Therefore, the resulting Ks - logP relations (PLRs) were compared with those from the LMC. The PLRs of NGC147 are in good agreement with the LMC relations. In contrast, a systematic shift of the sequence of fundamental mode pulsators (labeled as C) and the sequence for first overtone pulsators (C0) suggests a revised distance estimate for NGC185.
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- Nowotny, H, et al.
(författare)
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Therapy options for adrenal insufficiency and recommendations for the management of adrenal crisis
- 2021
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Ingår i: Endocrine. - : Springer Science and Business Media LLC. - 1559-0100 .- 1355-008X. ; 7371:23, s. 586-594
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Tidskriftsartikel (refereegranskat)abstract
- Adrenal insufficiency (AI) is a life-threatening condition requiring life-long glucocorticoid (GC) substitution therapy, as well as stress adaptation to prevent adrenal crises. The number of individuals with primary and secondary adrenal insufficiency in Europe is estimated to be 20–50/100.000. A growing number of AI cases are due to side effects of GC treatment used in different treatment strategies for cancer and to immunotherapy in cancer treatment. The benefit of hormone replacement therapy is evident but long-term adverse effects may arise due to the non-physiological GC doses and treatment regimens used. Given multiple GC replacement formulations available comprising short-acting, intermediate, long-acting and novel modified-release hydrocortisone as well as subcutaneous formulations, this review offers a concise summary on the latest therapeutic improvements for treatment of AI and prevention of adrenal crises. As availability of various glucocorticoid formulations and access to expert centers across Europe varies widely, European Reference Networks on rare endocrine conditions aim at harmonizing treatment and ensure access to specialized patient care for individual case-by-case treatment decisions. To improve the availability across Europe to cost effective oral and parenteral formulations of hydrocortisone will save lives.
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- Hren, A., et al.
(författare)
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Fluorine Abundances of AGB Stars in Stellar Clusters
- 2015
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Ingår i: WHY GALAXIES CARE ABOUT AGB STARS III. - : ASTRONOMICAL SOC PACIFIC. - 9781583818794 - 9781583818787 ; , s. 305-306
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Konferensbidrag (refereegranskat)abstract
- We have measured the abundance of fluorine, [F/Fe], in a number of AGB stars in stellar clusters have correlated the results with their C/O ratios. This allows us to investigate the change in the fluorine abundance along the evolution on the giant branch. The target list includes primarily O-rich stars in three LMC globular clusters - NGC 1806, NGC 1846 and NGC 1978 - as well as Rup 106 and 47 Tuc in our Galaxy. The observational data were obtained with the PHOENIX spectrograph, and the COMA code was used for modelling the synthetic spectra. Within individual clusters, we find consistent [F/Fe] values at similar C/O for most of our target stars.
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- Lebzelter, T., et al.
(författare)
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Abundance analysis for long-period variables II. RGB and AGB stars in the globular duster 47 Tucanae
- 2014
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 567, s. A143-
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Tidskriftsartikel (refereegranskat)abstract
- Context Asymptotic giant branch (AGB) stars play a key role in the enrichment of galaxies with heavy elements. Due to their large amplitude variability, the measurement of elemental abundances is a highly challenging task that has not been solved in a satisfactory V ay yet. Aims. Following our previous work we use hydrostatic and dynamical model atmospheres to simulate observed high-resolution near-infrared spectra of 12 variable and non variable red giants in the globular cluster 47 Tuc. The 47 Tuc red giants are independently well characterized in important parameters (mass, metallicity, luminosity). The principal aim was to compare synthetic spectra based on the dynamical models with observational spectra of 47 Ric variables. Assuming that the abundances are unchanged on the upper giant branch in these low-mass stars, our goal is to estimate the impact of atmospheric dynamics on the abundance determination. Methods. To estimate abundances we measured the equivalent widths of selected features in observed spectra and compared the results with predictions from a set of hydrostatic and dynamical model atmospheres resembling 47 Tun AGB stars in their fundamental parameters. Our study includes lines of (CO)-C-12, (CO)-C-13. OH, and Na. Furthermore, we investigated the variations in line intensities over a pulsation cycle. Results. We present new measurements of the C/O and C-12/C-13 ratio for 5 non variable red giants in 47 Tuc. The equivalent widths measured for our 7 variable star, strongly differ from the non variable stars arid cannot be reproduced by either hydrostatic or dynainical model atmospheres. Nevertheless, the dynamical models fit the observed spectra of long-period variables much better than any hydrostatic model. For some spectral features. the variations in the line intensities predicted by dynamical models over a pulsation cycle give similar values as a sequence of hydrostatic models with varying temperature and constant surface gravity. Conclusions. Our study of the dynamical effects on abundance determination visible in these well characterized cluster stars prepares the ground for the long-term goal of deriving abundarices for variable AGB stars in general.
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| 16. |
- Lebzelter, T., et al.
(författare)
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Abundance analysis for long period variables Velocity effects studied with O-rich dynamic model atmospheres
- 2010
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 517, s. A6-
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Tidskriftsartikel (refereegranskat)abstract
- Context. Measuring the surface abundances of AGB stars is an important tool for studying the effects of nucleosynthesis and mixing in the interior of low-to intermediate mass stars during their final evolutionary phases. The atmospheres of AGB stars can be strongly affected by stellar pulsation and the development of a stellar wind, though, and the abundance determination of these objects should therefore be based on dynamic model atmospheres. Aims. We investigate the effects of stellar pulsation and mass loss on the appearance of selected spectral features (line profiles, line intensities) and on the derived elemental abundances by performing a systematic comparison of hydrostatic and dynamic model atmospheres. Methods. High-resolution synthetic spectra in the near infrared range were calculated based on two dynamic model atmospheres (at various phases during the pulsation cycle) as well as a grid of hydrostatic COMARCS models with effective temperatures T-eff and surface gravities log g over an adequate range. Equivalent widths of a selection of atomic and molecular lines (Fe, OH, CO) were derived in both cases and compared with each other. Results. In the case of the dynamic models, the equivalent widths of all investigated features vary over the pulsation cycle. A consistent reproduction of the derived variations with a set of hydrostatic models is not possible, but several individual phases and spectral features can be reproduced well with the help of specific hydrostatic atmospheric models. In addition, we show that the variations in equivalent width that we found on the basis of the adopted state-of-the-art dynamic model atmospheres agree qualitatively with observational results for the Mira R Cas over its light cycle. Conclusions. The findings of our modelling form a starting point to deal with the problem of abundance determination in strongly dynamic AGB stars (i.e., long-period variables). Our results illustrate that some quantities such as the C/O ratio can probably still be determined to a reasonable accuracy, but the measurement of other quantities will be hampered by the dynamics. The qualitative agreement with observations of R Cas opens promising possibilities for a forthcoming quantitative comparison of our synthetic spectra with observed ones of AGB variables in the globular cluster 47 Tuc.
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| 17. |
- Lebzelter, T., et al.
(författare)
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Comparative modelling of the spectra of cool giants
- 2012
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 547, s. A108-
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Tidskriftsartikel (refereegranskat)abstract
- Context. Our ability to extract information from the spectra of stars depends on reliable models of stellar atmospheres and appropriate techniques for spectral synthesis. Various model codes and strategies for the analysis of stellar spectra are available today. Aims. We aim to compare the results of deriving stellar parameters using different atmosphere models and different analysis strategies. The focus is set on high-resolution spectroscopy of cool giant stars. Methods. Spectra representing four cool giant stars were made available to various groups and individuals working in the area of spectral synthesis, asking them to derive stellar parameters from the data provided. The results were discussed at a workshop in Vienna in 2010. Most of the major codes currently used in the astronomical community for analyses of stellar spectra were included in this experiment. Results. We present the results from the different groups, as well as an additional experiment comparing the synthetic spectra produced by various codes for a given set of stellar parameters. Similarities and differences of the results are discussed. Conclusions. Several valid approaches to analyze a given spectrum of a star result in quite a wide range of solutions. The main causes for the differences in parameters derived by different groups seem to lie in the physical input data and in the details of the analysis method. This clearly shows how far from a definitive abundance analysis we still are.
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| 18. |
- Lebzelter, T., et al.
(författare)
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The Challenges of Abundance Analysis for Long-Period Variables
- 2015
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Ingår i: WHY GALAXIES CARE ABOUT AGB STARS III. - : ASTRONOMICAL SOC PACIFIC. ; , s. 283-288
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Konferensbidrag (refereegranskat)abstract
- The measurement of elemental abundances of Asymptotic Giant Branch (AGB) stars is a highly challenging task that so far has not been solved in a satisfactory way. We report here on our efforts to confront predictions from hydrostatic and dynamical model atmospheres with observational results based on high-resolution spectra of variable and non-variable giants in the globular cluster 47 Tuc. Our goal is to estimate the impact of atmospheric dynamics on the abundance determination.
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| 23. |
- Wittkowski, M., et al.
(författare)
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Aperture synthesis imaging of the carbon AGB star R Sculptoris: Detection of a complex structure and a dominating spot on the stellar disk
- 2017
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 601
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Tidskriftsartikel (refereegranskat)abstract
- Aims. We present near-infrared interferometry of the carbon-rich asymptotic giant branch (AGB) star R Sculptoris (R Scl). Methods. We employ medium spectral resolution K-band interferometry obtained with the instrument AMBER at the Very Large Telescope Interferometer (VLTI) and H-band low spectral resolution interferometric imaging observations obtained with the VLTI instrument PIONIER. We compare our data to a recent grid of dynamic atmosphere and wind models. We compare derived fundamental parameters to stellar evolution models. Results. The visibility data indicate a broadly circular resolved stellar disk with a complex substructure. The observed AMBER squared visibility values show drops at the positions of CO and CN bands, indicating that these lines form in extended layers above the photosphere. The AMBER visibility values are best fit by a model without a wind. The PIONIER data are consistent with the same model. We obtain a Rosseland angular diameter of 8.9 ± 0.3 mas, corresponding to a Rosseland radius of 355 ± 55 R?, an effective temperature of 2640 ± 80 K, and a luminosity of log L/L? = 3.74 ± 0.18. These parameters match evolutionary tracks of initial mass 1.5 ± 0.5 M? and current mass 1.3 ± 0.7 M?. The reconstructed PIONIER images exhibit a complex structure within the stellar disk including a dominant bright spot located at the western part of the stellar disk. The spot has an H-band peak intensity of 40% to 60% above the average intensity of the limb-darkening-corrected stellar disk. The contrast between the minimum and maximum intensity on the stellar disk is about 1:2.5. Conclusions. Our observations are broadly consistent with predictions by dynamic atmosphere and wind models, although models with wind appear to have a circumstellar envelope that is too extended compared to our observations. The detected complex structure within the stellar disk is most likely caused by giant convection cells, resulting in large-scale shock fronts, and their effects on clumpy molecule and dust formation seen against the photosphere at distances of 2-3 stellar radii. © ESO, 2017.
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