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Sökning: WFRF:(Walther Thomas) > (2020-2024)

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1.
  • Menkveld, Albert J., et al. (författare)
  • Nonstandard Errors
  • 2024
  • Ingår i: JOURNAL OF FINANCE. - : Wiley-Blackwell. - 0022-1082 .- 1540-6261. ; 79:3, s. 2339-2390
  • Tidskriftsartikel (refereegranskat)abstract
    • In statistics, samples are drawn from a population in a data-generating process (DGP). Standard errors measure the uncertainty in estimates of population parameters. In science, evidence is generated to test hypotheses in an evidence-generating process (EGP). We claim that EGP variation across researchers adds uncertainty-nonstandard errors (NSEs). We study NSEs by letting 164 teams test the same hypotheses on the same data. NSEs turn out to be sizable, but smaller for more reproducible or higher rated research. Adding peer-review stages reduces NSEs. We further find that this type of uncertainty is underestimated by participants.
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2.
  • Kattge, Jens, et al. (författare)
  • TRY plant trait database - enhanced coverage and open access
  • 2020
  • Ingår i: Global Change Biology. - : Wiley-Blackwell. - 1354-1013 .- 1365-2486. ; 26:1, s. 119-188
  • Tidskriftsartikel (refereegranskat)abstract
    • Plant traits-the morphological, anatomical, physiological, biochemical and phenological characteristics of plants-determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits-almost complete coverage for 'plant growth form'. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait-environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives.
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3.
  • Akiyama, Kazunori, et al. (författare)
  • First Sagittarius A* Event Horizon Telescope Results. II. EHT and Multiwavelength Observations, Data Processing, and Calibration
  • 2022
  • Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8213 .- 2041-8205. ; 930:2
  • Tidskriftsartikel (refereegranskat)abstract
    • We present Event Horizon Telescope (EHT) 1.3 mm measurements of the radio source located at the position of the supermassive black hole Sagittarius A* (Sgr A*), collected during the 2017 April 5-11 campaign. The observations were carried out with eight facilities at six locations across the globe. Novel calibration methods are employed to account for Sgr A*'s flux variability. The majority of the 1.3 mm emission arises from horizon scales, where intrinsic structural source variability is detected on timescales of minutes to hours. The effects of interstellar scattering on the image and its variability are found to be subdominant to intrinsic source structure. The calibrated visibility amplitudes, particularly the locations of the visibility minima, are broadly consistent with a blurred ring with a diameter of similar to 50 mu as, as determined in later works in this series. Contemporaneous multiwavelength monitoring of Sgr A* was performed at 22, 43, and 86 GHz and at near-infrared and X-ray wavelengths. Several X-ray flares from Sgr A* are detected by Chandra, one at low significance jointly with Swift on 2017 April 7 and the other at higher significance jointly with NuSTAR on 2017 April 11. The brighter April 11 flare is not observed simultaneously by the EHT but is followed by a significant increase in millimeter flux variability immediately after the X-ray outburst, indicating a likely connection in the emission physics near the event horizon. We compare Sgr A*'s broadband flux during the EHT campaign to its historical spectral energy distribution and find that both the quiescent emission and flare emission are consistent with its long-term behavior.
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4.
  • Kim, Jae-Young, et al. (författare)
  • Event Horizon Telescope imaging of the archetypal blazar 3C 279 at an extreme 20 microarcsecond resolution
  • 2020
  • Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 640
  • Tidskriftsartikel (refereegranskat)abstract
    • 3C 279 is an archetypal blazar with a prominent radio jet that show broadband flux density variability across the entire electromagnetic spectrum. We use an ultra-high angular resolution technique - global Very Long Baseline Interferometry (VLBI) at 1.3mm (230 GHz) - to resolve the innermost jet of 3C 279 in order to study its fine-scale morphology close to the jet base where highly variable-ray emission is thought to originate, according to various models. The source was observed during four days in April 2017 with the Event Horizon Telescope at 230 GHz, including the phased Atacama Large Millimeter/submillimeter Array, at an angular resolution of ∼20 μas (at a redshift of z = 0:536 this corresponds to ∼0:13 pc ∼ 1700 Schwarzschild radii with a black hole mass MBH = 8 × 108 M⊙). Imaging and model-fitting techniques were applied to the data to parameterize the fine-scale source structure and its variation.We find a multicomponent inner jet morphology with the northernmost component elongated perpendicular to the direction of the jet, as imaged at longer wavelengths. The elongated nuclear structure is consistent on all four observing days and across diffierent imaging methods and model-fitting techniques, and therefore appears robust. Owing to its compactness and brightness, we associate the northern nuclear structure as the VLBI "core". This morphology can be interpreted as either a broad resolved jet base or a spatially bent jet.We also find significant day-to-day variations in the closure phases, which appear most pronounced on the triangles with the longest baselines. Our analysis shows that this variation is related to a systematic change of the source structure. Two inner jet components move non-radially at apparent speeds of ∼15 c and ∼20 c (∼1:3 and ∼1:7 μas day-1, respectively), which more strongly supports the scenario of traveling shocks or instabilities in a bent, possibly rotating jet. The observed apparent speeds are also coincident with the 3C 279 large-scale jet kinematics observed at longer (cm) wavelengths, suggesting no significant jet acceleration between the 1.3mm core and the outer jet. The intrinsic brightness temperature of the jet components are ≤1010 K, a magnitude or more lower than typical values seen at ≥7mm wavelengths. The low brightness temperature and morphological complexity suggest that the core region of 3C 279 becomes optically thin at short (mm) wavelengths.
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5.
  • Ludwig, Sebastian, et al. (författare)
  • Transcatheter Mitral Valve Replacement versus Medical Therapy for Secondary Mitral Regurgitation: A Propensity Score-Matched Comparison.
  • 2023
  • Ingår i: Circulation. Cardiovascular interventions. - 1941-7632. ; 16:6
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Transcatheter mitral valve replacement (TMVR) is an emerging therapeutic alternative for patients with secondary mitral regurgitation (MR). Outcomes of TMVR versus guideline-directed medical therapy (GDMT) have not been investigated for this population. This study aimed to compare clinical outcomes of patients with secondary MR undergoing TMVR versus GDMT alone. Methods: The CHOICE-MI registry included patients with MR undergoing TMVR using dedicated devices. Patients with MR etiologies other than secondary MR were excluded. Patients treated with GDMT alone were derived from the control arm of the COAPT trial. We compared outcomes between the TMVR and GDMT groups, using propensity score (PS)-matching to adjust for baseline differences. Results: After PS-matching, 97 patient pairs undergoing TMVR (72.9±8.7 years, 60.8% male, transapical access 91.8%) versus GDMT (73.1±11.0 years, 59.8% male) were compared. At 1 and 2 years, residual MR was ≤1+ in all patients of the TMVR group compared to 6.9% and 7.7%, respectively, in those receiving GDMT alone (both p<0.001). The 2-year rate of HF hospitalization was significantly lower in the TMVR group (32.8% vs. 54.4%, HR 0.59, 95% CI 0.35-0.99; p=0.04). Among survivors, a higher proportion of patients were in NYHA functional class I or II in the TMVR group at 1 year (78.2% vs. 59.7%, p=0.03) and at 2 years (77.8% vs. 53.2%, p=0.09). Two-year mortality was similar in the two groups (TMVR vs. GDMT, 36.8% vs. 40.8%, HR 1.01, 95% CI 0.62-1.64; p=0.98). Conclusions: In this observational comparison, over 2-year follow-up, TMVR using mostly transapical devices in patients with secondary MR was associated with significant reduction of MR, symptomatic improvement, less frequent hospitalizations for HF and similar mortality compared with GDMT.
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6.
  • Ahmed, Sheikh Ali, Senior Lecturer, 1977-, et al. (författare)
  • Resonance and time-of-flight methods for evaluating the modulus of elasticity of particleboards at different humid conditions
  • 2020
  • Ingår i: Wood research. - Slovakia : Slovak Forest Products Research Institute. - 1336-4561. ; 65:3, s. 365-380
  • Tidskriftsartikel (refereegranskat)abstract
    • Non-destructive testing of wood panels by either resonance or time-of-flight (TOF) methods provides possibilities for predicting their static bending properties. In the present study, three non-destructive devices (BING - Beam Identification by Non-destructive Grading by CIRAD, Montpellier, France, Fakopp Ultrasonic Timer and Sylvatest TRIO) were used for measuring the dynamic stiffness of different particleboard types. Fakopp Ultrasonic Timer and Sylvatest TRIO produce ultrasonic pulses to measure the sound velocity while BING uses resonance frequencies. Commercially produced particleboards with different thickness and densities were used to measure the dynamic modulus of elasticity (MOEdyn) in two directions (parallel and perpendicular to the production line) and at three different humidity levels (dry - 35%, standard - 65% and wet - 85% RH in constant temperature of 20°C ). MOEdyn of particleboards were correlated with the static moduli of elasticity (MOEstat) and rupture (MORstat). It was found that the non-destructive methods gave higher MOEdyn values in both production directions than that of MOEstat values. MOEdyn was found to decrease from dry to wet conditions. A very strong and statistically significant correlation existed between MOEdyn and static bending properties. MOEdyn correlated stronger to MOEstat than MORstat. At different humidity level, all three methods- Fakopp Ultrasonic Timer, BING and Sylvatest TRIO analyses showed good predicting capabilities to estimate MOEstat and MORstat of different particleboard types with high level of accuracy.
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7.
  • Forslund, Sofia K., et al. (författare)
  • Combinatorial, additive and dose-dependent drug–microbiome associations
  • 2021
  • Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 600:7889, s. 500-505
  • Tidskriftsartikel (refereegranskat)abstract
    • During the transition from a healthy state to cardiometabolic disease, patients become heavily medicated, which leads to an increasingly aberrant gut microbiome and serum metabolome, and complicates biomarker discovery1–5. Here, through integrated multi-omics analyses of 2,173 European residents from the MetaCardis cohort, we show that the explanatory power of drugs for the variability in both host and gut microbiome features exceeds that of disease. We quantify inferred effects of single medications, their combinations as well as additive effects, and show that the latter shift the metabolome and microbiome towards a healthier state, exemplified in synergistic reduction in serum atherogenic lipoproteins by statins combined with aspirin, or enrichment of intestinal Roseburia by diuretic agents combined with beta-blockers. Several antibiotics exhibit a quantitative relationship between the number of courses prescribed and progression towards a microbiome state that is associated with the severity of cardiometabolic disease. We also report a relationship between cardiometabolic drug dosage, improvement in clinical markers and microbiome composition, supporting direct drug effects. Taken together, our computational framework and resulting resources enable the disentanglement of the effects of drugs and disease on host and microbiome features in multimedicated individuals. Furthermore, the robust signatures identified using our framework provide new hypotheses for drug–host–microbiome interactions in cardiometabolic disease.
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8.
  • Hosseinpourpia, Reza, 1983-, et al. (författare)
  • Hydrophobic Formulations Based on Tall Oil Distillation Products for High-Density Fiberboards
  • 2020
  • Ingår i: Materials. - : MDPI. - 1996-1944. ; 13:18, s. 1-13
  • Tidskriftsartikel (refereegranskat)abstract
    • This study investigates the effect of renewable formulations based on tall oil bio-refinery products on the water vapor sorption and interfiber strength of cellulosic fibers as well as on the properties of high-density fiberboard (HDF) panels. The results obtained for HDF prepared using renewable formulations were compared to the results for HDF obtained using conventional synthetic paraffin wax (hydrowax), which is the hydrophobic agent currently utilized by the industry. Four tall oil distillation products (TODPs) with different levels of fatty and rosin acids were used for preparing the hydrophobic formulations with furfuryl alcohol as an organic solvent. According to determinations with an automated vapor sorption apparatus, the formulations had a similar effect with hydrowax on the sorption behavior of natural fibers. Unlike to hydrowax treatment, the ultimate tensile strength of cellulosic paper-sheets treated with the formulations remained unchanged or significantly increased. At the standard addition load of 1% (wt/wt dry fibers) of the formulations, HDF panels showed comparable and only in one case, e.g., TODP3-based formulation, slightly higher thickness swelling (24 h) than those with hydrowax. The best performing formulation (TODP2-based) in terms of tensile strength of paper sheets did not significantly change the mechanical properties of HDF panels in both standard climate and high humid conditions. Promising results at the standard and humid climate conditions were obtained for HDF panels manufactured with higher TODP2-based formulation amounts (3-5%) and reduced melamine-urea-formaldehyde resin content (10-12% instead of 14%, wt dry resin/wt dry fibers).
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9.
  • Jiang, Wen, et al. (författare)
  • Properties and Emissions of Three-Layer Particleboards Manufactured with Mixtures of Wood Chips and Partially Liquefied Bark
  • 2023
  • Ingår i: Materials. - : MDPI. - 1996-1944. ; 16:5
  • Tidskriftsartikel (refereegranskat)abstract
    • Partial liquefaction of residual biomass shows good potential for developing new materials suitable for making bio-based composites. Three-layer particleboards were produced by replacing virgin wood particles with partially liquefied bark (PLB) in the core or surface layers. PLB was prepared by the acid-catalyzed liquefaction of industrial bark residues in polyhydric alcohol. The chemical and microscopic structure of bark and residues after liquefaction were evaluated by means of Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM), while the particleboards were tested for their mechanical and water-related properties, as well as their emission profiles. Through a partial liquefaction process, some FTIR absorption peaks of the bark residues were lower than those of raw bark, indicating hydrolysis of chemical compounds. The surface morphology of bark did not change considerably after partial liquefaction. Particleboards with PLB in the core layers showed overall lower densities and mechanical properties (modulus of elasticity, modulus of rupture, and internal bond strength), and were less water-resistant as compared to the ones with PLB used in the surface layers. Formaldehyde emissions from the particleboards were 0.284–0.382 mg/m2·h, and thus, below the E1 class limit required by European Standard EN 13986:2004. The major emissions of volatile organic compounds (VOCs) were carboxylic acids as oxidization and degradation products from hemicelluloses and lignin. The application of PLB in three-layer particleboards is more challenging than in single-layer boards as PLB has different effects on the core and surface layers.
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10.
  • Lauridsen, Susanne Vahr, et al. (författare)
  • Effect of a Smoking and Alcohol Cessation Intervention Initiated Shortly Before Radical Cystectomy—the STOP-OP Study : A Randomised Clinical Trial
  • 2022
  • Ingår i: European Urology Focus. - : Elsevier BV. - 2405-4569. ; 8:6, s. 1650-1658
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Evidence concerning the reduction of postoperative complications due to smoking and alcohol drinking in patients undergoing radical cystectomy is incomplete. Objective: To evaluate the efficacy of a 6-wk smoking and/or alcohol cessation intervention, initiated shortly before surgery and continued until 4 wk after, in reducing complications. Design, setting, and participants: Between 2014 and 2018, we enrolled 104 patients with high-risk bladder cancer who were daily smokers or consuming at least 3 units of alcohol daily in a multicentre randomised clinical trial. Intervention: Patients were randomised to a 6-wk intensive smoking and/or alcohol cessation intervention or treatment as usual. Outcome measurements and statistical analysis: The primary endpoint was the number of patients developing any postoperative complication, or death, within 30 d after surgery. The secondary endpoints were successful quitters, health-related quality of life, length of stay, time back to habitual activity, and mortality. An intention-to-treat analysis was applied to evaluate treatment effect. Results and limitations: There were some differences in baseline demographic and lifestyle characteristics. Postoperatively, 64% in the intervention group versus 70% in the control group (risk ratio [RR] 0.91, confidence interval [CI] 0.68–1.21, p = 0.51) developed complications. Significantly fewer patients developed three or more complications after 30 d (RR 0.39; CI 0.18–0.84, p = 0.01). The rates of successful quitting were 51% in the intervention group and 27% in the control group (RR 2, CI 1.14–3.51, p = 0.01). The external validity of this trial may be limited because 53% of eligible patients refused participation. Conclusions: Despite a significant effect on the quit rate at completion of the intervention, this multimodal prehabilitation did not show a significant difference regarding our primary outcome postoperative complications. Patient summary: A 6-wk smoking and alcohol cessation intervention in relation to bladder cancer surgery did not reduce postoperative complications, but it was effective in supporting people to quit in the short term.
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