| 1. |
- Niemi, MEK, et al.
(författare)
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- 2021
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swepub:Mat__t
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| 2. |
- Kanai, M, et al.
(författare)
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- 2023
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swepub:Mat__t
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| 3. |
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| 4. |
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| 6. |
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| 7. |
- 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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| 8. |
- Axfors, Cathrine, et al.
(författare)
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Association between convalescent plasma treatment and mortality in COVID-19 : a collaborative systematic review and meta-analysis of randomized clinical trials
- 2021
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Ingår i: BMC Infectious Diseases. - : BioMed Central (BMC). - 1471-2334. ; 21:1
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Forskningsöversikt (refereegranskat)abstract
- Background: Convalescent plasma has been widely used to treat COVID-19 and is under investigation in numerous randomized clinical trials, but results are publicly available only for a small number of trials. The objective of this study was to assess the benefits of convalescent plasma treatment compared to placebo or no treatment and all-cause mortality in patients with COVID-19, using data from all available randomized clinical trials, including unpublished and ongoing trials (Open Science Framework, ). Methods: In this collaborative systematic review and meta-analysis, clinical trial registries (ClinicalTrials.gov, WHO International Clinical Trials Registry Platform), the Cochrane COVID-19 register, the LOVE database, and PubMed were searched until April 8, 2021. Investigators of trials registered by March 1, 2021, without published results were contacted via email. Eligible were ongoing, discontinued and completed randomized clinical trials that compared convalescent plasma with placebo or no treatment in COVID-19 patients, regardless of setting or treatment schedule. Aggregated mortality data were extracted from publications or provided by investigators of unpublished trials and combined using the Hartung-Knapp-Sidik-Jonkman random effects model. We investigated the contribution of unpublished trials to the overall evidence. Results: A total of 16,477 patients were included in 33 trials (20 unpublished with 3190 patients, 13 published with 13,287 patients). 32 trials enrolled only hospitalized patients (including 3 with only intensive care unit patients). Risk of bias was low for 29/33 trials. Of 8495 patients who received convalescent plasma, 1997 died (23%), and of 7982 control patients, 1952 died (24%). The combined risk ratio for all-cause mortality was 0.97 (95% confidence interval: 0.92; 1.02) with between-study heterogeneity not beyond chance (I-2 = 0%). The RECOVERY trial had 69.8% and the unpublished evidence 25.3% of the weight in the meta-analysis. Conclusions: Convalescent plasma treatment of patients with COVID-19 did not reduce all-cause mortality. These results provide strong evidence that convalescent plasma treatment for patients with COVID-19 should not be used outside of randomized trials. Evidence synthesis from collaborations among trial investigators can inform both evidence generation and evidence application in patient care.
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| 9. |
- Dankiewicz, Josef, et al.
(författare)
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Hypothermia versus Normothermia after Out-of-Hospital Cardiac Arrest
- 2021
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Ingår i: New England Journal of Medicine. - : MASSACHUSETTS MEDICAL SOC. - 0028-4793 .- 1533-4406. ; 384:24, s. 2283-2294
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Tidskriftsartikel (refereegranskat)abstract
- Hypothermia or Normothermia after Cardiac Arrest This trial randomly assigned patients with coma after out-of-hospital cardiac arrest to undergo targeted hypothermia at 33 degrees C or normothermia with treatment of fever. At 6 months, there were no significant between-group differences regarding death or functional outcomes. Background Targeted temperature management is recommended for patients after cardiac arrest, but the supporting evidence is of low certainty. Methods In an open-label trial with blinded assessment of outcomes, we randomly assigned 1900 adults with coma who had had an out-of-hospital cardiac arrest of presumed cardiac or unknown cause to undergo targeted hypothermia at 33 degrees C, followed by controlled rewarming, or targeted normothermia with early treatment of fever (body temperature, >= 37.8 degrees C). The primary outcome was death from any cause at 6 months. Secondary outcomes included functional outcome at 6 months as assessed with the modified Rankin scale. Prespecified subgroups were defined according to sex, age, initial cardiac rhythm, time to return of spontaneous circulation, and presence or absence of shock on admission. Prespecified adverse events were pneumonia, sepsis, bleeding, arrhythmia resulting in hemodynamic compromise, and skin complications related to the temperature management device. Results A total of 1850 patients were evaluated for the primary outcome. At 6 months, 465 of 925 patients (50%) in the hypothermia group had died, as compared with 446 of 925 (48%) in the normothermia group (relative risk with hypothermia, 1.04; 95% confidence interval [CI], 0.94 to 1.14; P=0.37). Of the 1747 patients in whom the functional outcome was assessed, 488 of 881 (55%) in the hypothermia group had moderately severe disability or worse (modified Rankin scale score >= 4), as compared with 479 of 866 (55%) in the normothermia group (relative risk with hypothermia, 1.00; 95% CI, 0.92 to 1.09). Outcomes were consistent in the prespecified subgroups. Arrhythmia resulting in hemodynamic compromise was more common in the hypothermia group than in the normothermia group (24% vs. 17%, P<0.001). The incidence of other adverse events did not differ significantly between the two groups. Conclusions In patients with coma after out-of-hospital cardiac arrest, targeted hypothermia did not lead to a lower incidence of death by 6 months than targeted normothermia. (Funded by the Swedish Research Council and others; TTM2 ClinicalTrials.gov number, .)
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| 10. |
- Betoule, M., et al.
(författare)
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Improved cosmological constraints from a joint analysis of the SDSS-II and SNLS supernova samples
- 2014
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 568, s. A22-
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Tidskriftsartikel (refereegranskat)abstract
- Aims. We present cosmological constraints from a joint analysis of type la supernova (SN Ia) observations obtained by the SDSS-II and SNLS collaborations. The dataset includes several low-redshift samples (z < 0.1), all three seasons from the SDSS-11 (0.05 < z < 0.4), and three years from SNLS (0.2 < z < 1), and it totals 740 spectroscopically confirmed type la supernovae with high quality light curves. Methods. We followed the methods and assumptions of the SNLS three-year data analysis except for the following important improvements: I) the addition of the full SDSS-II spectroscopically-confirmed SN la sample in both the training of the SALT2 light-curve model and in the Hubble diagram analysis (374 SNe); 2) intercalibration of the SNLS and SDSS surveys and reduced systematic uncertainties in the photometric calibration, performed blindly with respect to the cosmology analysis; and 3) a thorough investigation of systematic errors associated with the SALT2 modeling of SN la light curves. Results. We produce recalibrated SN la light curves and associated distances for the SDSS-II and SNLS samples. The large SOSS-II sample provides an effective, independent, low -z anchor for the Hubble diagram and reduces the systematic error from calibration systematics in the low -z SN sample. For a flat ACDM cosmology, we find Omega(m), = 0.295 0.034 (stat+sys), a value consistent with the most recent cosmic microwave background (CMB) measurement from the Planck and WMAP experiments. Our result is 1.8 sigma (stat+sys) different than the previously published result of SNLS three-year data. The change is due primarily to improvements in the SNLS photometric calibration. When combined with CMB constraints, we measure a constant dark energy equation of state parameter omega = -1.018 +/- 0,057 (sral+sys) for a fiat universe. Adding baryon acoustic oscillation distance measurements gives similar constraints: omega = 59 -1.027 0.055. Our supernova measurements provide the most stringent constraints to date on the nature of dark energy.
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| 11. |
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| 12. |
- Zhang, Y., et al.
(författare)
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Galaxies in X-ray selected clusters and groups in Dark Energy Survey data - II. Hierarchical Bayesian modelling of the red-sequence galaxy luminosity function
- 2019
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Ingår i: Monthly notices of the Royal Astronomical Society. - : OXFORD UNIV PRESS. - 0035-8711 .- 1365-2966. ; 488:1, s. 1-17
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Tidskriftsartikel (refereegranskat)abstract
- Using similar to 100 X-ray selected clusters in the Dark Energy Survey Science Verification data, we constrain the luminosity function ( LF) of cluster red-sequence galaxies as a function of redshift. This is the first homogeneous optical/X-ray sample large enough to constrain the evolution of the LF simultaneously in redshift ( 0.1 < z < 1.05) and cluster mass ( 13.5 <= log(10)( M-200crit) similar to< 15.0). We pay particular attention to completeness issues and the detection limit of the galaxy sample. We then apply a hierarchical Bayesian model to fit the cluster galaxy LFs via a Schechter function, including its characteristic break ( m*) to a faint end power-law slope ( alpha). Our method enables us to avoid known issues in similar analyses based on stacking or binning the clusters. We find weak and statistically insignificant (similar to 1.9 sigma) evolution in the faint end slope alpha versus redshift. We also find no dependence in alpha or m* with the X-ray inferred cluster masses. However, the amplitude of the LF as a function of cluster mass is constrained to similar to 20 per cent precision. As a by-product of our algorithm, we utilize the correlation between the LF and cluster mass to provide an improved estimate of the individual cluster masses as well as the scatter in true mass given the X-ray inferred masses. This technique can be applied to a larger sample of X-ray or optically selected clusters from the Dark Energy Survey, significantly improving the sensitivity of the analysis.
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| 13. |
- Aguilar, J. A., et al.
(författare)
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Triboelectric backgrounds to radio-based polar ultra-high energy neutrino (UHEN) experiments
- 2023
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Ingår i: Astroparticle physics. - : Elsevier. - 0927-6505 .- 1873-2852. ; 145
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Tidskriftsartikel (refereegranskat)abstract
- In the hopes of observing the highest-energy neutrinos (E> 1 EeV) populating the Universe, both past (RICE, AURA, ANITA) and current (RNO-G, ARIANNA, ARA and TAROGE-M) polar-sited experiments exploit the impulsive radio emission produced by neutrino interactions. In such experiments, rare single event candidates must be unambiguously identified above backgrounds. Background rejection strategies to date primarily target thermal noise fluctuations and also impulsive radio-frequency signals of anthropogenic origin. In this paper, we consider the possibility that 'fake' neutrino signals may also be generated naturally via the `triboelectric effect' This broadly describes any process in which force applied at a boundary layer results in displacement of surface charge, leading to the production of an electrostatic potential difference AV. Wind blowing over granular surfaces such as snow can induce such a potential difference, with subsequent coronal discharge. Discharges over timescales as short as nanoseconds can then lead to radio-frequency emissions at characteristic MHz-GHz frequencies. Using data from various past (RICE, AURA, SATRA, ANITA) and current (RNO G, ARIANNA and ARA) neutrino experiments, we find evidence for such backgrounds, which are generally characterized by: (a) a threshold wind velocity which likely depends on the experimental trigger criteria and layout; for the experiments considered herein, this value is typically O(10 m/s), (b) frequency spectra generally shifted to the low-end of the frequency regime to which current radio experiments are typically sensitive (100-200 MHz), (c) for the strongest background signals, an apparent preference for discharges from above-surface structures, although the presence of more isotropic, lower amplitude triboelectric discharges cannot be excluded.
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| 14. |
- Blanton, Michael R., et al.
(författare)
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Sloan Digital Sky Survey IV : Mapping the Milky Way, Nearby Galaxies, and the Distant Universe
- 2017
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Ingår i: Astronomical Journal. - : IOP Publishing Ltd. - 0004-6256 .- 1538-3881. ; 154:1
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Tidskriftsartikel (refereegranskat)abstract
- We describe the Sloan Digital Sky Survey IV (SDSS-IV), a project encompassing three major spectroscopic programs. The Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2) is observing hundreds of thousands of Milky Way stars at high resolution and. high signal-to-noise ratios in the near-infrared. The Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey is obtaining spatially resolved spectroscopy for thousands of nearby galaxies (median z similar to 0.03). The extended Baryon Oscillation Spectroscopic Survey (eBOSS) is mapping the galaxy, quasar, and neutral gas distributions between z similar to 0.6 and 3.5 to constrain cosmology using baryon acoustic oscillations, redshift space distortions, and the shape of the power spectrum. Within eBOSS, we are conducting two major subprograms: the SPectroscopic IDentification of eROSITA Sources (SPIDERS), investigating X-ray AGNs. and galaxies in X-ray clusters, and the Time Domain Spectroscopic Survey (TDSS), obtaining spectra of variable sources. All programs use the 2.5 m Sloan Foundation Telescope at the. Apache Point Observatory; observations there began in Summer 2014. APOGEE-2 also operates a second near-infrared spectrograph at the 2.5 m du Pont Telescope at Las Campanas Observatory, with observations beginning in early 2017. Observations at both facilities are scheduled to continue through 2020. In keeping with previous SDSS policy, SDSS-IV provides regularly scheduled public data releases; the first one, Data Release 13, was made available in 2016 July.
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| 15. |
- Axfors, Cathrine, et al.
(författare)
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Mortality outcomes with hydroxychloroquine and chloroquine in COVID-19 from an international collaborative meta-analysis of randomized trials
- 2021
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Ingår i: Nature Communications. - : Springer Nature. - 2041-1723. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- Substantial COVID-19 research investment has been allocated to randomized clinical trials (RCTs) on hydroxychloroquine/chloroquine, which currently face recruitment challenges or early discontinuation. We aim to estimate the effects of hydroxychloroquine and chloroquine on survival in COVID-19 from all currently available RCT evidence, published and unpublished. We present a rapid meta-analysis of ongoing, completed, or discontinued RCTs on hydroxychloroquine or chloroquine treatment for any COVID-19 patients (protocol: https://osf.io/QESV4/). We systematically identified unpublished RCTs (ClinicalTrials.gov, WHO International Clinical Trials Registry Platform, Cochrane COVID-registry up to June 11, 2020), and published RCTs (PubMed, medRxiv and bioRxiv up to October 16, 2020). All-cause mortality has been extracted (publications/preprints) or requested from investigators and combined in random-effects meta-analyses, calculating odds ratios (ORs) with 95% confidence intervals (CIs), separately for hydroxychloroquine and chloroquine. Prespecified subgroup analyses include patient setting, diagnostic confirmation, control type, and publication status. Sixty-three trials were potentially eligible. We included 14 unpublished trials (1308 patients) and 14 publications/preprints (9011 patients). Results for hydroxychloroquine are dominated by RECOVERY and WHO SOLIDARITY, two highly pragmatic trials, which employed relatively high doses and included 4716 and 1853 patients, respectively (67% of the total sample size). The combined OR on all-cause mortality for hydroxychloroquine is 1.11 (95% CI: 1.02, 1.20; I-2=0%; 26 trials; 10,012 patients) and for chloroquine 1.77 (95%CI: 0.15, 21.13, I-2=0%; 4 trials; 307 patients). We identified no subgroup effects. We found that treatment with hydroxychloroquine is associated with increased mortality in COVID-19 patients, and there is no benefit of chloroquine. Findings have unclear generalizability to outpatients, children, pregnant women, and people with comorbidities. Hydroxychloroquine and chloroquine have been investigated as a potential treatment for Covid-19 in several clinical trials. Here the authors report a meta-analysis of published and unpublished trials, and show that treatment with hydroxychloroquine for patients with Covid-19 was associated with increased mortality, and there was no benefit from chloroquine.
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| 16. |
- Abolfathi, Bela, et al.
(författare)
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The Fourteenth Data Release of the Sloan Digital Sky Survey : First Spectroscopic Data from the Extended Baryon Oscillation Spectroscopic Survey and from the Second Phase of the Apache Point Observatory Galactic Evolution Experiment
- 2018
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Ingår i: Astrophysical Journal Supplement Series. - : IOP Publishing Ltd. - 0067-0049 .- 1538-4365. ; 235:2
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Tidskriftsartikel (refereegranskat)abstract
- The fourth generation of the Sloan Digital Sky Survey (SDSS-IV) has been in operation since 2014 July. This paper describes the second data release from this phase, and the 14th from SDSS overall (making this Data Release Fourteen or DR14). This release makes the data taken by SDSS-IV in its first two years of operation (2014-2016 July) public. Like all previous SDSS releases, DR14 is cumulative, including the most recent reductions and calibrations of all data taken by SDSS since the first phase began operations in 2000. New in DR14 is the first public release of data from the extended Baryon Oscillation Spectroscopic Survey; the first data from the second phase of the Apache Point Observatory (APO) Galactic Evolution Experiment (APOGEE-2), including stellar parameter estimates from an innovative data-driven machine-learning algorithm known as "The Cannon"; and almost twice as many data cubes from the Mapping Nearby Galaxies at APO (MaNGA) survey as were in the previous release (N = 2812 in total). This paper describes the location and format of the publicly available data from the SDSS-IV surveys. We provide references to the important technical papers describing how these data have been taken (both targeting and observation details) and processed for scientific use. The SDSS web site (www.sdss.org) has been updated for this release and provides links to data downloads, as well as tutorials and examples of data use. SDSS-IV is planning to continue to collect astronomical data until 2020 and will be followed by SDSS-V.
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| 17. |
- Astier, P., et al.
(författare)
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Extending the supernova Hubble diagram to z similar to 1.5 with the Euclid space mission
- 2014
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 572, s. A80-
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Tidskriftsartikel (refereegranskat)abstract
- We forecast dark energy constraints that could be obtained from a new large sample of Type Ia supernovae where those at high redshift are acquired with the Euclid space mission. We simulate a three-prong SN survey: a z < 0.35 nearby sample (8000 SNe), a 0.2 < z < 0.95 intermediate sample (8800 SNe), and a 0.75 < z < 1.55 high-z sample (1700 SNe). The nearby and intermediate surveys are assumed to be conducted from the ground, while the high-z is a joint ground-and space-based survey. This latter survey, the Dark Energy Supernova Infra-Red Experiment (DESIRE), is designed to fit within 6 months of Euclid observing time, with a dedicated observing programme. We simulate the SN events as they would be observed in rolling-search mode by the various instruments, and derive the quality of expected cosmological constraints. We account for known systematic uncertainties, in particular calibration uncertainties including their contribution through the training of the supernova model used to fit the supernovae light curves. Using conservative assumptions and a 1D geometric Planck prior, we find that the ensemble of surveys would yield competitive constraints: a constant equation of state parameter can be constrained to sigma(omega) = 0.022, and a Dark Energy Task Force figure of merit of 203 is found for a two-parameter equation of state. Our simulations thus indicate that Euclid can bring a significant contribution to a purely geometrical cosmology constraint by extending a high-quality SN Ia Hubble diagram to z similar to 1.5. We also present other science topics enabled by the DESIRE Euclid observations.
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| 18. |
- Dankiewicz, Josef, et al.
(författare)
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Targeted hypothermia versus targeted Normothermia after out-of-hospital cardiac arrest (TTM2): A randomized clinical trial - Rationale and design
- 2019
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Ingår i: American Heart Journal. - : Elsevier BV. - 0002-8703 .- 1097-6744. ; 217, s. 23-31
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Tidskriftsartikel (refereegranskat)abstract
- Background: Less than 500 participants have been included in randomized trials comparing hypothermia with regular care for out-of-hospital cardiac arrest patients, and many of these trials were small and at a high risk of bias. Consequently, the accrued data on this potentially beneficial intervention resembles that of a drug following small phase II trials. A large confirmatory trial is therefore warranted. Methods: The TTM2-trial is an international, multicenter, parallel group, investigator-initiated, randomized, superiority trial in which a target temperature of 33°C after cardiac arrest will be compared with a strategy to maintain normothermia and early treatment of fever (≥37.8°C). Participants will be randomized within 3 hours of return of spontaneous circulation with the intervention period lasting 40 hours in both groups. Sedation will be mandatory for all patients throughout the intervention period. The clinical team involved with direct patient care will not be blinded to allocation group due to the inherent difficulty in blinding the intervention. Prognosticators, outcome-assessors, the steering group, the trial coordinating team, and trial statistician will be blinded. The primary outcome will be all-cause mortality at 180 days after randomization. We estimate a 55% mortality in the control group. To detect an absolute risk reduction of 7.5% with an alpha of 0.05 and 90% power, 1900 participants will be enrolled. The main secondary neurological outcome will be poor functional outcome (modified Rankin Scale 4–6) at 180 days after arrest. Discussion: The TTM2-trial will compare hypothermia to 33°C with normothermia and early treatment of fever (≥37.8°C) after out-of-hospital cardiac arrest. © 2019
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| 19. |
- Lampeitl, H., et al.
(författare)
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First-year Sloan Digital Sky Survey-II supernova results : consistency and constraints with other intermediate-redshift data sets
- 2010
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 401:4, s. 2331-2342
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Tidskriftsartikel (refereegranskat)abstract
- We present an analysis of the luminosity distances of Type Ia Supernovae (SNe) from the Sloan Digital Sky Survey-II (SDSS-II) SN Survey in conjunction with other intermediate-redshift (z < 0.4) cosmological measurements including redshift-space distortions from the Two-Degree Field Galaxy Redshift Survey (2dFGRS), the integrated Sachs–Wolfe (ISW) effect seen by the SDSS and the latest baryon acoustic oscillation (BAO) distance scale from both the SDSS and 2dFGRS. We have analysed the SDSS-II SN data alone using a variety of ‘model-independent’ methods and find evidence for an accelerating Universe at a >97 per cent level from this single data set. We find good agreement between the SN and BAO distance measurements, both consistent with a Λ-dominated cold dark matter cosmology, as demonstrated through an analysis of the distance duality relationship between the luminosity (dL) and angular diameter (dA) distance measures. We then use these data to estimate w within this restricted redshift range (z < 0.4). Our most stringent result comes from the combination of all our intermediate-redshift data (SDSS-II SNe, BAO, ISW and redshift-space distortions), giving w=−0.81+0.16−0.18 (stat) ± 0.15 (sys) and ΩM= 0.22+0.09−0.08 assuming a flat universe. This value of w and associated errors only change slightly if curvature is allowed to vary, consistent with constraints from the cosmic microwave background. We also consider more limited combinations of the geometrical (SN, BAO) and dynamical (ISW, redshift-space distortions) probes.
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| 20. |
- Sollerman, J., et al.
(författare)
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First-Year Sloan Digital Sky Survey-II (SDSS-II) Supernova Results : Constraints on Nonstandard Cosmological Models
- 2009
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 703:2, s. 1374-1385
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Tidskriftsartikel (refereegranskat)abstract
- We use the new Type Ia supernovae discovered by the Sloan Digital Sky Survey-II supernova survey, together with additional supernova data sets as well as observations of the cosmic microwave background and baryon acoustic oscillations to constrain cosmological models. This complements the standard cosmology analysis presented by Kessler et al. in that we discuss and rank a number of the most popular nonstandard cosmology scenarios. When this combined data set is analyzed using the MLCS2k2 light-curve fitter, we find that more exotic models for cosmic acceleration provide a better fit to the data than the ΛCDM model. For example, the flat Dvali-Gabadadze-Porrati model is ranked higher by our information-criteria (IC) tests than the standard model with a flat universe and a cosmological constant. When the supernova data set is instead analyzed using the SALT-II light-curve fitter, the standard cosmological-constant model fares best. This investigation of how sensitive cosmological model selection is to assumptions about, and within, the light-curve fitters thereby highlights the need for an improved understanding of these unresolved systematic effects. Our investigation also includes inhomogeneous Lemaître-Tolman-Bondi (LTB) models. While our LTB models can be made to fit the supernova data as well as any other model, the extra parameters they require are not supported by our IC analysis. Finally, we explore more model-independent ways to investigate the cosmic expansion based on this new data set.
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| 21. |
- Östman, Linda, et al.
(författare)
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NTT and NOT spectroscopy of SDSS-II supernovae
- 2011
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 526, s. A28-
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Tidskriftsartikel (refereegranskat)abstract
- Context. The Sloan Digital Sky Survey II (SDSS-II) Supernova Survey, conducted between 2005 and 2007, was designed to detect a large number of type Ia supernovae around z ~ 0.2, the redshift "gap" between low-z and high-z supernova searches. The survey has provided multi-band (ugriz) photometric lightcurves for variable targets, and supernova candidates were scheduled for spectroscopic observations, primarily to provide supernova classification and accurate redshifts. We present supernova spectra obtained in 2006 and 2007 using the New Technology Telescope (NTT) and the Nordic Optical Telescope (NOT). Aims: We provide an atlas of supernova spectra in the range z = 0.03-0.32 that complements the well-sampled lightcurves from SDSS-II in the forthcoming three-year SDSS supernova cosmology analysis. The sample can, for example, be used for spectral studies of type Ia supernovae, which are critical for understanding potential systematic effects when supernovae are used to determine cosmological distances. Methods: The spectra were reduced in a uniform manner, and special care was taken in estimating the uncertainties for the different processing steps. Host-galaxy light was subtracted when possible and the supernova type fitted using the SuperNova IDentification code (SNID). We also present comparisons between spectral and photometric dating using SALT lightcurve fits to the photometry from SDSS-II, as well as the global distribution of our sample in terms of the lightcurve parameters: stretch and colour. Results: We report new spectroscopic data from 141 type Ia supernovae, mainly between -9 and +15 days from lightcurve maximum, including a few cases of multi-epoch observations. This homogeneous, host-galaxy subtracted, type Ia supernova spectroscopic sample is among the largest such data sets and unique in its redshift interval. The sample includes two potential SN 1991T-like supernovae (SN 2006on and SN 2007ni) and one potential SN 2002cx-like supernova (SN 2007ie). In addition, the new compilation includes spectra from 23 confirmed type II and 8 type Ib/c supernovae.
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| 22. |
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| 23. |
- Robba, C., et al.
(författare)
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Ventilation management and outcomes in out-of-hospital cardiac arrest: a protocol for a preplanned secondary analysis of the TTM2 trial
- 2022
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Ingår i: BMJ Open. - : BMJ. - 2044-6055. ; 12:3
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Tidskriftsartikel (refereegranskat)abstract
- Introduction Mechanical ventilation is a fundamental component in the management of patients post cardiac arrest. However, the ventilator settings and the gas-exchange targets used after cardiac arrest may not be optimal to minimise post-anoxic secondary brain injury. Therefore, questions remain regarding the best ventilator management in such patients. Methods and analysis This is a preplanned analysis of the international randomised controlled trial, targeted hypothermia versus targeted normothermia after out-of-hospital cardiac arrest (OHCA)-target temperature management 2 (TTM2). The primary objective is to describe ventilatory settings and gas exchange in patients who required invasive mechanical ventilation and included in the TTM2 trial. Secondary objectives include evaluating the association of ventilator settings and gas-exchange values with 6 months mortality and neurological outcome. Adult patients after an OHCA who were included in the TTM2 trial and who received invasive mechanical ventilation will be eligible for this analysis. Data collected in the TTM2 trial that will be analysed include patients' prehospital characteristics, clinical examination, ventilator settings and arterial blood gases recorded at hospital and intensive care unit (ICU) admission and daily during ICU stay. Ethics and dissemination The TTM2 study has been approved by the regional ethics committee at Lund University and by all relevant ethics boards in participating countries. No further ethical committee approval is required for this secondary analysis. Data will be disseminated to the scientific community by abstracts and by original articles submitted to peer-reviewed journals.
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| 24. |
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| 25. |
- Kousathanas, A, et al.
(författare)
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Whole-genome sequencing reveals host factors underlying critical COVID-19
- 2022
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 1476-4687 .- 0028-0836. ; 607:7917, s. 97-
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Tidskriftsartikel (refereegranskat)abstract
- Critical COVID-19 is caused by immune-mediated inflammatory lung injury. Host genetic variation influences the development of illness requiring critical care1 or hospitalization2–4 after infection with SARS-CoV-2. The GenOMICC (Genetics of Mortality in Critical Care) study enables the comparison of genomes from individuals who are critically ill with those of population controls to find underlying disease mechanisms. Here we use whole-genome sequencing in 7,491 critically ill individuals compared with 48,400 controls to discover and replicate 23 independent variants that significantly predispose to critical COVID-19. We identify 16 new independent associations, including variants within genes that are involved in interferon signalling (IL10RB and PLSCR1), leucocyte differentiation (BCL11A) and blood-type antigen secretor status (FUT2). Using transcriptome-wide association and colocalization to infer the effect of gene expression on disease severity, we find evidence that implicates multiple genes—including reduced expression of a membrane flippase (ATP11A), and increased expression of a mucin (MUC1)—in critical disease. Mendelian randomization provides evidence in support of causal roles for myeloid cell adhesion molecules (SELE, ICAM5 and CD209) and the coagulation factor F8, all of which are potentially druggable targets. Our results are broadly consistent with a multi-component model of COVID-19 pathophysiology, in which at least two distinct mechanisms can predispose to life-threatening disease: failure to control viral replication; or an enhanced tendency towards pulmonary inflammation and intravascular coagulation. We show that comparison between cases of critical illness and population controls is highly efficient for the detection of therapeutically relevant mechanisms of disease.
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| 26. |
- Leloudas, G., et al.
(författare)
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SN 2006oz : rise of a super-luminous supernova observed by the SDSS-II SN Survey
- 2012
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 541, s. A129-
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Tidskriftsartikel (refereegranskat)abstract
- Context. A new class of super-luminous transients has recently been identified. These objects reach absolute luminosities of M-u < -21, lack hydrogen in their spectra, and are exclusively discovered by non-targeted surveys because they are associated with very faint galaxies. Aims. We aim to contribute to a better understanding of these objects by studying SN 2006oz, a newly-recognized member of this class. Methods. We present multi-color light curves of SN 2006oz from the SDSS-II SN Survey that cover its rise time, as well as an optical spectrum that shows that the explosion occurred at z similar to 0.376. We fitted black-body functions to estimate the temperature and radius evolution of the photosphere and used the parametrized code SYNOW to model the spectrum. We constructed a bolometric light curve and compared it with explosion models. In addition, we conducted a deep search for the host galaxy with the 10 m GTC telescope. Results. The very early light curves show a dip in the g-and r-bands and a possible initial cooling phase in the u-band before rising to maximum light. The bolometric light curve shows a precursor plateau with a duration of 6-10 days in the rest-frame. A lower limit of M-u < -21.5 can be placed on the absolute peak luminosity of the SN, while the rise time is constrained to be at least 29 days. During our observations, the emitting sphere doubled its radius to similar to 2 x 10(15) cm, while the temperature remained hot at similar to 15 000 K. As for other similar SNe, the spectrum is best modeled with elements including O II and Mg II, while we tentatively suggest that Fe III might be present. The host galaxy is detected in gri with 25.74 +/- 0.19, 24.43 +/- 0.06, and 24.14 +/- 0.12, respectively. It is a faint dwarf galaxy with M-g = -16.9. Conclusions. We suggest that the precursor plateau might be related to a recombination wave in a circumstellar medium (CSM) and discuss whether this is a common property of all similar explosions. The subsequent rise can be equally well described by input from a magnetar or by ejecta-CSM interaction, but the models are not well constrained owing to the lack of post-maximum observations, and CSM interaction has difficulties accounting for the precursor plateau self-consistently. Radioactive decay is less likely to be the mechanism that powers the luminosity. The host is a moderately young and star-forming, but not a starburst, galaxy.
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| 27. |
- Mehrtens, N., et al.
(författare)
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The XMM Cluster Survey : the halo occupation number of BOSS galaxies in X-ray clusters
- 2016
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 463:2, s. 1929-1943
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Tidskriftsartikel (refereegranskat)abstract
- We present a direct measurement of the mean halo occupation distribution (HOD) of galaxies taken from the eleventh data release (DR11) of the Sloan Digital Sky Survey-III Baryon Oscillation Spectroscopic Survey (BOSS). The HOD of BOSS low-redshift (LOWZ: 0.2 < z < 0.4) and Constant-Mass (CMASS: 0.43 < z < 0.7) galaxies is inferred via their association with the dark matter haloes of 174 X-ray-selected galaxy clusters drawn from the XMM Cluster Survey (XCS). Halo masses are determined for each galaxy cluster based on X-ray temperature measurements, and range between log10(M180/M⊙) = 13 and 15. Our directly measured HODs are consistent with the HOD-model fits inferred via the galaxy-clustering analyses of Parejko et al. for the BOSS LOWZ sample and White et al. for the BOSS CMASS sample. Under the simplifying assumption that the other parameters that describe the HOD hold the values measured by these authors, we have determined a best-fitting alpha-index of 0.91 ± 0.08 and 1.27−0.04+0.03" role="presentation">1.27+0.03−0.04 for the CMASS and LOWZ HOD, respectively. These alpha-index values are consistent with those measured by White et al. and Parejko et al. In summary, our study provides independent support for the HOD models assumed during the development of the BOSS mock-galaxy catalogues that have subsequently been used to derive BOSS cosmological constraints.
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| 28. |
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| 29. |
- Nordin, Jakob, et al.
(författare)
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Spectral properties of Type Ia supernovae up to z~0.3
- 2011
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 526, s. A119-
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Tidskriftsartikel (refereegranskat)abstract
- Aims: Spectroscopic observations of type Ia supernovae obtained at the New Technology Telescope (NTT) and the Nordic Optical Telescope (NOT), in conjunction with the SDSS-II Supernova Survey, are analysed. We use spectral indicators measured up to a month after the lightcurve peak luminosity to characterise the supernova properties, and examine these for potential correlations with host galaxy type, lightcurve shape, colour excess, and redshift. Methods: Our analysis is based on 89 type Ia supernovae at a redshift interval z = 0.05-0.3, for which multiband SDSS photometry is available. A lower-z spectroscopy reference sample was used for comparisons over cosmic time. We present measurements of time series of pseudo equivalent widths and line velocities of the main spectral features in type Ia supernovae. Results: Supernovae with shallower features are found predominantly among the intrinsically brighter slow declining supernovae. We detect the strongest correlation between lightcurve stretch and the Si ii λ4000 absorption feature, which also correlates with the estimated mass and star formation rate of the host galaxy. We also report a tentative correlation between colour excess and spectral properties. If confirmed, this would suggest that moderate reddening of type Ia supernovae is dominated by effects in the explosion or its immediate environment, as opposed to extinction by interstellar dust.
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| 30. |
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| 31. |
- Porcar-Castell, A., et al.
(författare)
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EUROSPEC: at the interface between remote-sensing and ecosystem CO2 flux measurements in Europe
- 2015
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Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4189. ; 12:20, s. 6103-6124
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Forskningsöversikt (refereegranskat)abstract
- Resolving the spatial and temporal dynamics of gross primary productivity (GPP) of terrestrial ecosystems across different scales remains a challenge. Remote sensing is regarded as the solution to upscale point observations conducted at the ecosystem level, using the eddy covariance (EC) technique, to the landscape and global levels. In addition to traditional vegetation indices, the photochemical reflectance index (PRI) and the emission of solar-induced chlorophyll fluorescence (SIF), now measurable from space, provide a new range of opportunities to monitor the global carbon cycle using remote sensing. However, the scale mismatch between EC observations and the much coarser satellite-derived data complicates the integration of the two sources of data. The solution is to establish a network of in situ spectral measurements that can act as bridge between EC measurements and remote sensing data. In situ spectral measurements have been already conducted for many years at EC sites, but using variable instrumentation, setups, and measurement standards. In Europe in particular, in situ spectral measurements remain highly heterogeneous. The goal of EUROSPEC Cost Action ES0930 was to promote the development of common measuring protocols and new instruments towards establishing best practices and standardization of in situ spectral measurements. In this review we describe the background and main tradeoffs of in situ spectral measurements, review the main results of EUROSPEC Cost Action, and discuss the future challenges and opportunities of in situ spectral measurements for improved estimation of local and global carbon cycle.
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| 32. |
- Prentice, S. J., et al.
(författare)
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SN 2018gjx reveals that some SNe Ibn are SNe IIb exploding in dense circumstellar material
- 2020
-
Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 499:1, s. 1450-1467
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Tidskriftsartikel (refereegranskat)abstract
- We present the data and analysis of SN 2018gjx, an unusual low-luminosity transient with three distinct spectroscopic phases. Phase I shows a hot blue spectrum with signatures of ionized circumstellar material (CSM), Phase II has the appearance of broad SN features, consistent with those seen in a Type IIb supernova at maximum light, and Phase III is that of a supernova interacting with helium-rich CSM, similar to a Type Ibn supernova. This event provides an apparently rare opportunity to view the inner workings of an interacting supernova. The observed properties can be explained by the explosion of a star in an aspherical CSM. The initial light is emitted from an extended CSM (similar to 4000 R-circle dot), which ionizes the exterior unshocked material. Some days after, the SN photosphere envelops this region, leading to the appearance of a SN IIb. Over time, the photosphere recedes in velocity space, revealing interaction between the supernova ejecta and the CSM that partially obscures the supernova nebular phase. Modelling of the initial spectrum reveals a surface composition consistent with compact H-deficient Wolf-Rayet and Luminous Blue Variable (LBV) stars. Such configurations may not be unusual, with SNe IIb being known to have signs of interaction so at least some SNe IIb and SNe Ibn may be the same phenomena viewed from different angles, or possibly with differing CSM configurations.
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| 33. |
- Stott, J. P., et al.
(författare)
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THE XMM CLUSTER SURVEY : THE BUILD-UP OF STELLAR MASS IN BRIGHTEST CLUSTER GALAXIES AT HIGH REDSHIFT
- 2010
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 718:1, s. 23-30
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Tidskriftsartikel (refereegranskat)abstract
- We present deep J-and K-s-band photometry of 20 high redshift galaxy clusters between z = 0.8 and 1.5, 19 of which are observed with the MOIRCS instrument on the Subaru telescope. By using near-infrared light as a proxy for stellar mass we find the surprising result that the average stellar mass of Brightest Cluster Galaxies (BCGs) has remained constant at similar to 9 x 10(11) M-circle dot since z similar to 1.5. We investigate the effect on this result of differing star formation histories generated by three well-known and independent stellar population codes and find it to be robust for reasonable, physically motivated choices of age and metallicity. By performing Monte Carlo simulations we find that the result is unaffected by any correlation between BCG mass and cluster mass in either the observed or model clusters. The large stellar masses imply that the assemblage of these galaxies took place at the same time as the initial burst of star formation. This result leads us to conclude that dry merging has had little effect on the average stellar mass of BCGs over the last 9-10 Gyr in stark contrast to the predictions of semi-analytic models, based on the hierarchical merging of dark matter halos, which predict a more protracted mass build-up over a Hubble time. However, we discuss that there is potential for reconciliation between observation and theory if there is a significant growth of material in the intracluster light over the same period.
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| 34. |
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| 35. |
- Chong, S S, et al.
(författare)
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Contribution of DNA sequence and CAG size to mutation frequencies of intermediate alleles for Huntington disease : evidence from single sperm analyses.
- 1997
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Ingår i: Human Molecular Genetics. - : Oxford University Press (OUP). - 0964-6906 .- 1460-2083. ; 6:2, s. 301-9
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Tidskriftsartikel (refereegranskat)abstract
- New mutations for Huntington disease (HD) arise from intermediate alleles (IAs) with between 29 and 35 CAG repeats that expand on transmission through the paternal germline to 36 CAGs or greater. Using single sperm analysis, we have assessed CAG mutation frequencies for four IAs in families with sporadic HD (IANM) and IAs ascertained from the general population (IAGP) by analyzing 1161 single sperm from three persons. We show that IANM are more unstable than IAGP with identical size and sequence. Furthermore, comparison of different sized IAs and IAs with different sequences between the CAG and the adjacent CCG tracts indicates that DNA sequence is a major influence on CAG stability. These studies provide estimates of the likelihood of expansion of IANM and IAGP to > or = 36 CAG repeats for these individuals. For an IA with a CAG of 35 in this family with sporadic HD, the likelihood for siblings to inherit a recurrent mutation > or = 36 CAG is approximately 10%. For IAGP of a similar size, the risk of inheriting an expanded allele of > or = 36 CAG through the paternal germline is approximately 6%. These risk estimates are higher than previously reported and provide additional information for counselling in these families. Further studies on persons with IAs will be needed to determine whether these results can be generalized to other families.
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| 36. |
- Dyson, Kylie, et al.
(författare)
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International variation in survival after out-of-hospital cardiac arrest : A validation study of the Utstein template.
- 2019
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Ingår i: Resuscitation. - : Elsevier BV. - 0300-9572 .- 1873-1570. ; 138, s. 168-181
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Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION: Out-of-hospital cardiac arrest (OHCA) survival varies greatly between communities. The Utstein template was developed and promulgated to improve the comparability of OHCA outcome reports, but it has undergone limited empiric validation. We sought to assess how much of the variation in OHCA survival between emergency medical services (EMS) across the globe is explained by differences in the Utstein factors. We also assessed how accurately the Utstein factors predict OHCA survival.METHODS: We performed a retrospective analysis of patient-level prospectively collected data from 12 OHCA registries from 12 countries for the period 1 Jan 2006 through 31 Dec 2011. We used generalized linear mixed models to examine the variation in survival between EMS agencies (n=232).RESULTS: Twelve registries contributed 86,759 cases. Patient arrest characteristics, EMS treatment and patient outcomes varied across registries. Overall survival to hospital discharge was 10% (range, 6% to 22%). Overall survival with Cerebral Performance Category of 1 or 2 (available for 8/12 registries) was 8% (range, 2% to 20%). The area-under-the-curve for the Utstein model was 0.85 (Wald CI: 0.85-0.85). The Utstein factors explained 51% of the EMS agency variation in OHCA survival.CONCLUSIONS: The Utstein factors explained 51% of the variation in survival to hospital discharge among multiple large geographically separate EMS agencies. This suggests that quality improvement and public health efforts should continue to target modifiable Utstein factors to improve OHCA survival. Further study is required to identify the reasons for the variation that is incompletely understood.
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| 37. |
- Kessler, Richard, et al.
(författare)
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First-Year Sloan Digital Sky Survey-II Supernova Results : Hubble Diagram and Cosmological Parameters
- 2009
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Ingår i: Astrophysical Journal Supplement Series. - : American Astronomical Society. - 0067-0049 .- 1538-4365. ; 185:1, s. 32-84
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Tidskriftsartikel (refereegranskat)abstract
- We present measurements of the Hubble diagram for 103 Type Ia supernovae (SNe) with redshifts 0.04 < z < 0.42, discovered during the first season (Fall 2005) of the Sloan Digital Sky Survey-II (SDSS-II) Supernova Survey. These data fill in the redshift "desert" between low- and high-redshift SN Ia surveys. Within the framework of the MLCS2K2 light-curve fitting method, we use the SDSS-II SN sample to infer the mean reddening parameter for host galaxies, RV = 2.18 ± 0.14stat ± 0.48syst, and find that the intrinsic distribution of host-galaxy extinction is well fitted by an exponential function, P(AV ) = exp(-AV /τV), with τV = 0.334 ± 0.088 mag. We combine the SDSS-II measurements with new distance estimates for published SN data from the ESSENCE survey, the Supernova Legacy Survey (SNLS), the Hubble Space Telescope (HST), and a compilation of Nearby SN Ia measurements. A new feature in our analysis is the use of detailed Monte Carlo simulations of all surveys to account for selection biases, including those from spectroscopic targeting. Combining the SN Hubble diagram with measurements of baryon acoustic oscillations from the SDSS Luminous Red Galaxy sample and with cosmic microwave background temperature anisotropy measurements from the Wilkinson Microwave Anisotropy Probe, we estimate the cosmological parameters w and ΩM, assuming a spatially flat cosmological model (FwCDM) with constant dark energy equation of state parameter, w. We also consider constraints upon ΩM and ΩΛ for a cosmological constant model (ΛCDM) with w = -1 and non-zero spatial curvature. For the FwCDM model and the combined sample of 288 SNe Ia, we find w = -0.76 ± 0.07(stat) ± 0.11(syst), ΩM = 0.307 ± 0.019(stat) ± 0.023(syst) using MLCS2K2 and w = -0.96 ± 0.06(stat) ± 0.12(syst), ΩM = 0.265 ± 0.016(stat) ± 0.025(syst) using the SALT-II fitter. We trace the discrepancy between these results to a difference in the rest-frame UV model combined with a different luminosity correction from color variations; these differences mostly affect the distance estimates for the SNLS and HST SNe. We present detailed discussions of systematic errors for both light-curve methods and find that they both show data-model discrepancies in rest-frame U band. For the SALT-II approach, we also see strong evidence for redshift-dependence of the color-luminosity parameter (β). Restricting the analysis to the 136 SNe Ia in the Nearby+SDSS-II samples, we find much better agreement between the two analysis methods but with larger uncertainties: w = -0.92 ± 0.13(stat)+0.10 -0.33(syst) for MLCS2K2 and w = -0.92 ± 0.11(stat)+0.07 -0.15 (syst) for SALT-II.
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| 38. |
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| 39. |
- Nishiyama, C, et al.
(författare)
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Apples to apples or apples to oranges? International variation in reporting of process and outcome of care for out-of-hospital cardiac arrest
- 2014
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Ingår i: Resuscitation. - : Elsevier Ireland Ltd.. - 0300-9572 .- 1873-1570. ; 85:11, s. 1599-1609
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: Survival after out-of-hospital cardiac arrest (OHCA) varies between communities, due in part to variation in the methods of measurement. The Utstein template was disseminated to standardize comparisons of risk factors, quality of care, and outcomes in patients with OHCA. We sought to assess whether OHCA registries are able to collate common data using the Utstein template. A subsequent study will assess whether the Utstein factors explain differences in survival between emergency medical services (EMS) systems. STUDY DESIGN: Retrospective study. SETTING: This retrospective analysis of prospective cohorts included adults treated for OHCA, regardless of the etiology of arrest. Data describing the baseline characteristics of patients, and the process and outcome of their care were grouped by EMS system, de-identified, and then collated. Included were core Utstein variables and timed event data from each participating registry. This study was classified as exempt from human subjects' research by a research ethics committee. MEASUREMENTS AND MAIN RESULTS: Thirteen registries with 265 first-responding EMS agencies in 13 countries contributed data describing 125,840 cases of OHCA. Variation in inclusion criteria, definition, coding, and process of care variables were observed. Contributing registries collected 61.9% of recommended core variables and 42.9% of timed event variables. Among core variables, the proportion of missingness was mean 1.9±2.2%. The proportion of unknown was mean 4.8±6.4%. Among time variables, missingness was mean 9.0±6.3%. CONCLUSIONS: International differences in measurement of care after OHCA persist. Greater consistency would facilitate improved resuscitation care and comparison within and between communities.
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| 40. |
- Nordin, Jakob, et al.
(författare)
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EVIDENCE FOR A CORRELATION BETWEEN THE Si II lambda 4000 WIDTH AND TYPE Ia SUPERNOVA COLOR
- 2011
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 734:1, s. 42-
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Tidskriftsartikel (refereegranskat)abstract
- We study the pseudo-equivalent width of the Si II lambda 4000 feature of Type Ia supernovae (SNe Ia) in the redshift range 0.0024 <= z <= 0.634. We find that this spectral indicator correlates with the light curve color excess (SALT2c) as well as previously defined spectroscopic subclasses (Branch types) and the evolution of the Si II lambda 6150 velocity, i.e., the so-called velocity gradient. Based on our study of 55 objects from different surveys, we find indications that the Si II lambda 4000 spectral indicator could provide important information to improve cosmological distance measurements with SNe Ia.
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| 41. |
- Nordin, Jakob, et al.
(författare)
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Evidence for a correlation between the SiII λ4000 width and Type Ia supernova color
-
Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357.
-
Tidskriftsartikel (refereegranskat)abstract
- We study the pseudo equivalent width of the SiII λ4000 feature of Type Iasupernovae (SNe Ia) in the redshift range 0.0024 ≤z ≤0.634. We find that this spectral indicator correlateswith the light curve color excess SALT2 c as well as previouslydefined spectroscopic subclasses (Branch types) and theevolution of the SiII λ6150 velocity, i.e., the so called velocitygradient. Based on our study of 55 objects from different surveys, we find indications that the SiII λ4000 spectral indicatorcould provide important information to improve cosmological distancemeasurements with SNe Ia.
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| 42. |
- Almqvist, E, et al.
(författare)
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Ancestral differences in the distribution of the delta 2642 glutamic acid polymorphism is associated with varying CAG repeat lengths on normal chromosomes : insights into the genetic evolution of Huntington disease.
- 1995
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Ingår i: Human Molecular Genetics. - : Oxford University Press (OUP). - 0964-6906 .- 1460-2083. ; 4:2, s. 207-14
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Tidskriftsartikel (refereegranskat)abstract
- This study addresses genetic factors associated with normal variation of the CAG repeat in the Huntington disease (HD) gene. To achieve this, we have studied patterns of variation of three trinucleotide repeats in the HD gene including the CAG and adjacent CCG repeats as well as a GAG polymorphism at residue 2642 (delta 2642). We have previously demonstrated that variation in the CCG repeat is associated with variation of the CAG repeat length on normal chromosomes. Here we show that differences in the GAG trinucleotide polymorphism at residue 2642 is also significantly correlated with CAG size on normal chromosomes. The B allele which is associated with higher CAG repeat lengths on normal chromosomes is markedly enriched on affected chromosomes. Furthermore, this glutamic acid polymorphism shows significant variation in different ancestries and is absent in chromosomes of Japanese, Black and Chinese descent. Haplotype analysis of both the CCG and delta 2642 polymorphisms have indicated that both are independently associated with differences in CAG length on normal chromosomes. These findings lead to a model for the genetic evolution of new mutations for HD preferentially occurring on normal chromosomes with higher CAG repeat lengths and a CCG repeat length of seven and/or a deletion of the glutamic acid residue at delta 2642. This study also provides additional evidence for genetic contributions to demographic differences in prevalence rates for HD.
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| 43. |
- Balzarolo, Manuela, et al.
(författare)
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Ground-Based Optical Measurements at European Flux Sites: A Review of Methods, Instruments and Current Controversies
- 2011
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Ingår i: Sensors. - : MDPI AG. - 1424-8220. ; 11:8, s. 7954-7981
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Forskningsöversikt (refereegranskat)abstract
- This paper reviews the currently available optical sensors, their limitations and opportunities for deployment at Eddy Covariance (EC) sites in Europe. This review is based on the results obtained from an online survey designed and disseminated by the Co-cooperation in Science and Technology (COST) Action ESO903-"Spectral Sampling Tools for Vegetation Biophysical Parameters and Flux Measurements in Europe" that provided a complete view on spectral sampling activities carried out within the different research teams in European countries. The results have highlighted that a wide variety of optical sensors are in use at flux sites across Europe, and responses further demonstrated that users were not always fully aware of the key issues underpinning repeatability and the reproducibility of their spectral measurements. The key findings of this survey point towards the need for greater awareness of the need for standardisation and development of a common protocol of optical sampling at the European EC sites.
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| 44. |
- Davis, Tamara M., et al.
(författare)
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The Effect of Peculiar Velocities on Supernova Cosmology
- 2011
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 741, s. 67-
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Tidskriftsartikel (refereegranskat)abstract
- We analyze the effect that peculiar velocities have on the cosmological inferences we make using luminosity distance indicators, such as Type Ia supernovae. In particular we study the corrections required to account for (1) our own motion, (2) correlations in galaxy motions, and (3) a possible local under- or overdensity. For all of these effects we present a case study showing the impact on the cosmology derived by the Sloan Digital Sky Survey-II Supernova Survey (SDSS-II SN Survey). Correcting supernova (SN) redshifts for the cosmic microwave background (CMB) dipole slightly overcorrects nearby SNe that share some of our local motion. We show that while neglecting the CMB dipole would cause a shift in the derived equation of state of Δw ~ 0.04 (at fixed Ω m ), the additional local-motion correction is currently negligible (Δw <~ 0.01). We then demonstrate a covariance-matrix approach to statistically account for correlated peculiar velocities. This down-weights nearby SNe and effectively acts as a graduated version of the usual sharp low-redshift cut. Neglecting coherent velocities in the current sample causes a systematic shift of Δw ~ 0.02. This will therefore have to be considered carefully when future surveys aim for percent-level accuracy and we recommend our statistical approach to down-weighting peculiar velocities as a more robust option than a sharp low-redshift cut.
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| 45. |
- Dilday, Benjamin, et al.
(författare)
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Measurements of the Rate of Type Ia Supernovae at Redshift lsim0.3 from the Sloan Digital Sky Survey II Supernova Survey
- 2010
-
Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 713, s. 1026-1036
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Tidskriftsartikel (refereegranskat)abstract
- We present a measurement of the volumetric Type Ia supernova (SN Ia) rate based on data from the Sloan Digital Sky Survey II (SDSS-II) Supernova Survey. The adopted sample of supernovae (SNe) includes 516 SNe Ia at redshift z <~ 0.3, of which 270(52%) are spectroscopically identified as SNe Ia. The remaining 246 SNe Ia were identified through their light curves; 113 of these objects have spectroscopic redshifts from spectra of their host galaxy, and 133 have photometric redshifts estimated from the SN light curves. Based on consideration of 87 spectroscopically confirmed non-Ia SNe discovered by the SDSS-II SN Survey, we estimate that 2.04+1.61 -0.95% of the photometric SNe Ia may be misidentified. The sample of SNe Ia used in this measurement represents an order of magnitude increase in the statistics for SN Ia rate measurements in the redshift range covered by the SDSS-II Supernova Survey. If we assume an SN Ia rate that is constant at low redshift (z < 0.15), then the SN observations can be used to infer a value of the SN rate of rV = (2.69+0.34+0.21 -0.30-0.01)×10-5 SNe yr-1 Mpc-3 (H 0/(70 km s-1 Mpc-1))3 at a mean redshift of ~0.12, based on 79 SNe Ia of which 72 are spectroscopically confirmed. However, the large sample of SNe Ia included in this study allows us to place constraints on the redshift dependence of the SN Ia rate based on the SDSS-II Supernova Survey data alone. Fitting a power-law model of the SN rate evolution, rV (z) = Ap × ((1 + z)/(1 + z 0))ν, over the redshift range 0.0 < z < 0.3 with z 0 = 0.21, results in Ap = (3.43+0.15 -0.15) × 10-5 SNe yr-1 Mpc-3 (H 0/(70 km s-1 Mpc-1))3 and ν = 2.04+0.90 -0.89.
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| 46. |
- Fredriksson, M, et al.
(författare)
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Variation in outcome in studies of out-of-hospital cardiac arrest : a review of studies conforming to the Utstein guidelines
- 2003
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Ingår i: American Journal of Emergency Medicine. - : W.B. Saunders Co.. - 0735-6757 .- 1532-8171. ; 21:4, s. 276-281
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this study was to systematically review studies on out-of-hospital cardiac arrest published according to the Utstein guidelines to describe the variability in factors of resuscitation and outcome. Articles that reported primary data on survival after out-of-hospital cardiac arrest in the Utstein style were included. Forty-seven articles were identified using Medline. Fourteen studies met our criteria for inclusion. The number of patients in whom resuscitation was attempted varied between 78 and 3,243. The proportion of bystander-witnessed cases varied between 38% and 89%; bystander CPR was performed in 21% to 56% of the cases. Patients with a bystander-witnessed cardiac arrest of cardiac etiology were discharged alive in 2% to 49% of the cases. Even when data are reported in a uniform way as suggested by the Utstein template, there is a tremendous variability in outcome. This did not appear to be entirely explained by variability in the traditional risk factors for a low chance of survival. One cannot exclude the possibility of other factors being of ultimate importance for the outcome.
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| 47. |
- Hayden, Brian T., et al.
(författare)
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Single or Double Degenerate Progenitors? Searching for Shock Emission in the SDSS-II Type Ia Supernovae
- 2010
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 722:2, s. 1691-1698
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Tidskriftsartikel (refereegranskat)abstract
- From the set of nearly 500 spectroscopically confirmed Type Ia supernovae (SNe) and around 10,000 unconfirmed candidates from SDSS-II, we select a subset of 108 confirmed SNe Ia with well-observed early-time light curves to search for signatures from shock interaction of the SN with a companion star. No evidence for shock emission is seen; however, the cadence and photometric noise could hide a weak shock signal. We simulate shocked light curves using SN Ia templates and a simple Gaussian shock model to emulate the noise properties of the SDSS-II sample and estimate the detectability of the shock interaction signal as a function of shock amplitude, shock width, and shock fraction. We find no direct evidence for shock interaction in the rest-frame B-band, but place an upper limit on the shock amplitude at 9% of SN peak flux (MB > - 16.6 mag). If the single degenerate channel dominates type Ia progenitors, this result constrains the companion stars to be less than about 6 M sun on the main sequence and strongly disfavors red giant companions.
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| 48. |
- Hayden, Brian T., et al.
(författare)
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The Rise and Fall of Type Ia Supernova Light Curves in the SDSS-II Supernova Survey
- 2010
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 712:1, s. 350-366
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Tidskriftsartikel (refereegranskat)abstract
- We analyze the rise and fall times of Type Ia supernova (SN Ia) light curves discovered by the Sloan Digital Sky Survey-II (SDSS-II) Supernova Survey. From a set of 391 light curves k-corrected to the rest-frame B and V bands, we find a smaller dispersion in the rising portion of the light curve compared to the decline. This is in qualitative agreement with computer models which predict that variations in radioactive nickel yield have less impact on the rise than on the spread of the decline rates. The differences we find in the rise and fall properties suggest that a single "stretch" correction to the light curve phase does not properly model the range of SN Ia light curve shapes. We select a subset of 105 light curves well observed in both rise and fall portions of the light curves and develop a "2-stretch" fit algorithm which estimates the rise and fall times independently. We find the average time from explosion to B-band peak brightness is 17.38 ± 0.17 days, but with a spread of rise times which range from 13 days to 23 days. Our average rise time is shorter than the 19.5 days found in previous studies; this reflects both the different light curve template used and the application of the 2-stretch algorithm. The SDSS-II supernova set and the local SNe Ia with well-observed early light curves show no significant differences in their average rise-time properties. We find that slow-declining events tend to have fast rise times, but that the distribution of rise minus fall time is broad and single peaked. This distribution is in contrast to the bimodality in this parameter that was first suggested by Strovink from an analysis of a small set of local SNe Ia. We divide the SDSS-II sample in half based on the rise minus fall value, tr - tf <= 2 days and tr - tf > 2 days, to search for differences in their host galaxy properties and Hubble residuals; we find no difference in host galaxy properties or Hubble residuals in our sample.
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| 49. |
- Holgersson, Johan, et al.
(författare)
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Hypothermic versus Normothermic Temperature Control after Cardiac Arrest
- 2022
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Ingår i: NEJM Evidence. - 2766-5526. ; 1:11, s. 1-13
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUNDThe evidence for temperature control for comatose survivors of cardiac arrest is inconclusive. Controversy exists as to whether the effects of hypothermia differ per the circumstances of the cardiac arrest or patient characteristics.METHODSAn individual patient data meta-analysis of the Targeted Temperature Management at 33°C versus 36°C after Cardiac Arrest (TTM) and Hypothermia versus Normothermia after Out-of-Hospital Cardiac Arrest (TTM2) trials was conducted. The intervention was hypothermia at 33°C and the comparator was normothermia. The primary outcome was all-cause mortality at 6 months. Secondary outcomes included poor functional outcome (modified Rankin scale score of 4 to 6) at 6 months. Predefined subgroups based on the design variables in the original trials were tested for interaction with the intervention as follows: age (older or younger than the median), sex (female or male), initial cardiac rhythm (shockable or nonshockable), time to return of spontaneous circulation (above or below the median), and circulatory shock on admission (presence or absence).RESULTSThe primary analyses included 2800 patients, with 1403 assigned to hypothermia and 1397 to normothermia. Death occurred for 691 of 1398 participants (49.4%) in the hypothermia group and 666 of 1391 participants (47.9%) in the normothermia group (relative risk with hypothermia, 1.03; 95% confidence interval [CI], 0.96 to 1.11; P=0.41). A poor functional outcome occurred for 733 of 1350 participants (54.3%) in the hypothermia group and 718 of 1330 participants (54.0%) in the normothermia group (relative risk with hypothermia, 1.01; 95% CI, 0.94 to 1.08; P=0.88). Outcomes were consistent in the predefined subgroups.CONCLUSIONSHypothermia at 33°C did not decrease 6-month mortality compared with normothermia after out-of-hospital cardiac arrest. (Funded by Vetenskapsrådet; ClinicalTrials.gov numbers NCT02908308 and NCT01020916.)
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