| 1. |
- Gerkin, RC, et al.
(author)
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The best COVID-19 predictor is recent smell loss: a cross-sectional study
- 2020
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In: medRxiv : the preprint server for health sciences. - : Cold Spring Harbor Laboratory.
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Journal article (other academic/artistic)abstract
- BackgroundCOVID-19 has heterogeneous manifestations, though one of the most common symptoms is a sudden loss of smell (anosmia or hyposmia). We investigated whether olfactory loss is a reliable predictor of COVID-19.MethodsThis preregistered, cross-sectional study used a crowdsourced questionnaire in 23 languages to assess symptoms in individuals self-reporting recent respiratory illness. We quantified changes in chemosensory abilities during the course of the respiratory illness using 0-100 visual analog scales (VAS) for participants reporting a positive (C19+; n=4148) or negative (C19-; n=546) COVID-19 laboratory test outcome. Logistic regression models identified singular and cumulative predictors of COVID-19 status and post-COVID-19 olfactory recovery.ResultsBoth C19+ and C19-groups exhibited smell loss, but it was significantly larger in C19+ participants (mean±SD, C19+: -82.5±27.2 points; C19-: -59.8±37.7). Smell loss during illness was the best predictor of COVID-19 in both single and cumulative feature models (ROC AUC=0.72), with additional features providing negligible model improvement. VAS ratings of smell loss were more predictive than binary chemosensory yes/no-questions or other cardinal symptoms, such as fever or cough. Olfactory recovery within 40 days was reported for ∼50% of participants and was best predicted by time since illness onset.ConclusionsAs smell loss is the best predictor of COVID-19, we developed the ODoR-19 tool, a 0-10 scale to screen for recent olfactory loss. Numeric ratings ≤2 indicate high odds of symptomatic COVID-19 (4<OR<10), which can be deployed when viral lab tests are impractical or unavailable.
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| 2. |
- Oleszkiewicz, A., et al.
(author)
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Hedonic perception of odors in children aged 5–8 years is similar across 18 countries : Preliminary data
- 2022
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In: International Journal of Pediatric Otorhinolaryngology. - : Elsevier BV. - 0165-5876 .- 1872-8464. ; 157
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Journal article (peer-reviewed)abstract
- Objective: Olfactory preference emerges very early in life, and the sense of smell in children rapidly develops until the second decade of life. It is still unclear whether hedonic perception of odors is shared in children inhabiting different regions of the globe.Methods: Five-hundred ten healthy children (N = 510; ngirls = 256; nboys = 254) aged from 5 to 8 years from 18 countries rated the pleasantness of 17 odors.Results: The hedonic perception of odors in children aged between 5 and 8 years was rather consistent across 18 countries and mainly driven by the qualities of an odor and the overall ability of children to label odorants.Conclusion: Conclusions from this study, being a secondary analysis, are limited to the presented set of odors that were initially selected for the development of U-Sniff test and present null findings for the cross-cultural variability in hedonic perception of odors across 18 countries. These two major issues should be addressed in the future to either contradict or replicate the results presented herewith. This research lays fundament for posing further research questions about the developmental aspects of hedonic perception of odors and opens a new door for investigating cross-cultural differences in chemosensory perception of children.
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| 3. |
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| 4. |
- Dent, W. R. F., et al.
(author)
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GASPS-A Herschel Survey of Gas and Dust in Protoplanetary Disks: Summary and Initial Statistics
- 2013
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In: Publications of the Astronomical Society of the Pacific. - : IOP Publishing. - 0004-6280 .- 1538-3873. ; 125:927, s. 477-505
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Journal article (peer-reviewed)abstract
- We describe a large-scale far-infrared line and continuum survey of protoplanetary disk through to young debris disk systems carried out using the ACS instrument on the Herschel Space Observatory. This Open Time Key program, known as GASPS (Gas Survey of Protoplanetary Systems), targeted similar to 250 young stars in narrow wavelength regions covering the [OI] fine structure line at 63 mu m the brightest far-infrared line in such objects. A subset of the brightest targets were also surveyed in [OI]145 mu m, [CII] at 157 mu m, as well as several transitions of H2O and high-excitation CO lines at selected wavelengths between 78 and 180 mu m. Additionally, GASPS included continuum photometry at 70, 100 and 160 mu m, around the peak of the dust emission. The targets were SED Class II-III T Tauri stars and debris disks from seven nearby young associations, along with a comparable sample of isolated Herbig AeBe stars. The aim was to study the global gas and dust content in a wide sample of circumstellar disks, combining the results with models in a systematic way. In this overview paper we review the scientific aims, target selection and observing strategy of the program. We summarise some of the initial results, showing line identifications, listing the detections, and giving a first statistical study of line detectability. The [OI] line at 63 mu m was the brightest line seen in almost all objects, by a factor of similar to 10. Overall [OI]63 mu m detection rates were 49%, with 100% of HAeBe stars and 43% of T Tauri stars detected. A comparison with published disk dust masses (derived mainly from sub-mm continuum, assuming standard values of the mm mass opacity) shows a dust mass threshold for [OI] 63 mu m detection of similar to 10(-5) M-circle dot. Normalising to a distance of 140 pc, 84% of objects with dust masses >= 10(-5) M-circle dot can be detected in this line in the present survey; 32% of those of mass 10(-6)-10(-5) M-circle dot, and only a very small number of unusual objects with lower masses can be detected. This is consistent with models with a moderate UV excess and disk flaring. For a given disk mass, [OI] detectability is lower for M stars compared with earlier spectral types. Both the continuum and line emission was, in most systems, spatially and spectrally unresolved and centred on the star, suggesting that emission in most cases was from the disk. Approximately 10 objects showed resolved emission, most likely from outflows. In the GASPS sample, [OI] detection rates in T Tauri associations in the 0.3-4 Myr age range were similar to 50%. For each association in the 5-20 Myr age range, similar to 2 stars remain detectable in [OI]63 mu m, and no systems were detected in associations with age >20 Myr. Comparing with the total number of young stars in each association, and assuming a ISM-like gas/dust ratio, this indicates that similar to 18% of stars retain a gas-rich disk of total mass similar to 1 M-Jupiter for 1-4 Myr, 1-7% keep such disks for 5-10 Myr, but none are detected beyond 10-20 Myr. The brightest [OI] objects from GASPS were also observed in [OI]145 mu m, [CII]157 mu m and CO J = 18 - 17, with detection rates of 20-40%. Detection of the [CII] line was not correlated with disk mass, suggesting it arises more commonly from a compact remnant envelope.
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| 5. |
- Mathews, G. S., et al.
(author)
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GAS in Protoplanetary Systems (GASPS) I. First results
- 2010
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In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 518:Article Number: L127
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Journal article (peer-reviewed)abstract
- Context. Circumstellar discs are ubiquitous around young stars, but rapidly dissipate their gas and dust on timescales of a few Myr. The Herschel Space Observatory allows for the study of the warm disc atmosphere, using far-infrared spectroscopy to measure gas content and excitation conditions, and far-IR photometry to constrain the dust distribution. Aims. We aim to detect and characterize the gas content of circumstellar discs in four targets as part of the Herschel science demonstration phase. Methods. We carried out sensitive medium resolution spectroscopy and high sensitivity photometry at gimel similar to 60-190 mu m using the Photodetector Array Camera and Spectrometer instrument on the Herschel Space Observatory. Results. We detect [OI] 63 mu m emission from the young stars HD 169142, TW Hydrae, and RECX 15, but not HD 181327. No other lines, including [CII] 158 and [OI] 145, are significantly detected. All four stars are detected in photometry at 70 and 160 mu m. Extensive models are presented in associated papers.
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| 6. |
- Meeus, G., et al.
(author)
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Gas in the protoplanetary disc of HD 169142: Herschel's view
- 2010
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In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 518:Article Number: L124
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Journal article (peer-reviewed)abstract
- In an effort to simultaneously study the gas and dust components of the disc surrounding the young Herbig Ae star HD 169142, we present far-IR observations obtained with the PACS instrument onboard the Herschel Space Observatory. This work is part of the open time key program GASPS, which is aimed at studying the evolution of protoplanetary discs. To constrain the gas properties in the outer disc, we observed the star at several key gas-lines, including [OI] 63.2 and 145.5 mu m, [CII] 157.7 mu m, CO 72.8 and 90.2 mu m, and o-H2O 78.7 and 179.5 mu m. We only detect the [OI] 63.2 mu m line in our spectra, and derive upper limits for the other lines. We complement our data set with PACS photometry and (CO)-C-12/13 data obtained with the Submillimeter Array. Furthermore, we derive accurate stellar parameters from optical spectra and UV to mm photometry. We model the dust continuum with the 3D radiative transfer code MCFOST and use this model as an input to analyse the gas lines with the thermo-chemical code ProDIMo. Our dataset is consistent with a simple model in which the gas and dust are well-mixed in a disc with a continuous structure between 20 and 200 AU, but this is not a unique solution. Our modelling effort allows us to constrain the gas-to-dust mass ratio as well as the relative abundance of the PAHs in the disc by simultaneously fitting the lines of several species that originate in different regions. Our results are inconsistent with a gas-poor disc with a large UV excess; a gas mass of 5.0 +/- 2.0 x 10(-3) M-circle dot is still present in this disc, in agreement with earlier CO observations.
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| 7. |
- Pinte, C., et al.
(author)
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The Herschel view of GAS in Protoplanetary Systems (GASPS) First comparisons with a large grid of models
- 2010
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In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 518:Article Number: L126
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Journal article (peer-reviewed)abstract
- The Herschel GASPS key program is a survey of the gas phase of protoplanetary discs, targeting 240 objects which cover a large range of ages, spectral types, and disc properties. To interpret this large quantity of data and initiate self-consistent analyses of the gas and dust properties of protoplanetary discs, we have combined the capabilities of the radiative transfer code MCFOST with the gas thermal balance and chemistry code ProDiMo to compute a grid of approximate to 300 000 disc models (DENT). We present a comparison of the first Herschel/GASPS line and continuum data with the predictions from the DENT grid of models. Our objective is to test some of the main trends already identified in the DENT grid, as well as to define better empirical diagnostics to estimate the total gas mass of protoplanetary discs. Photospheric UV radiation appears to be the dominant gas-heating mechanism for Herbig stars, whereas UV excess and/or X-rays emission dominates for T Tauri stars. The DENT grid reveals the complexity in the analysis of far-IR lines and the difficulty to invert these observations into physical quantities. The combination of Herschel line observations with continuum data and/or with rotational lines in the (sub-)millimetre regime, in particular CO lines, is required for a detailed characterisation of the physical and chemical properties of circumstellar discs.
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| 8. |
- Thi, W. F., et al.
(author)
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Herschel-PACS observation of the 10 Myr old T Tauri disk TW Hya Constraining the disk gas mass
- 2010
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In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 518:Article Number: L125
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Journal article (peer-reviewed)abstract
- Planets are formed in disks around young stars. With an age of similar to 10 Myr, TW Hya is one of the nearest T Tauri stars that is still surrounded by a relatively massive disk. In addition a large number of molecules has been found in the TW Hya disk, making TW Hya the perfect test case in a large survey of disks with Herschel-PACS to directly study their gaseous component. We aim to constrain the gas and dust mass of the circumstellar disk around TW Hya. We observed the fine-structure lines of [OI] and [CII] as part of the open-time large program GASPS. We complement this with continuum data and ground-based (12) CO 3-2 and (CO)-C-13 3-2 observations. We simultaneously model the continuum and the line fluxes with the 3D Monte-Carlo code MCFOST and the thermo-chemical code ProDiMo to derive the gas and dust masses. We detect the [OI] line at 63 mu m. The other lines that were observed, [OI] at 145 mu m and [CII] at 157 mu m, are not detected. No extended emission has been found. Preliminary modeling of the photometric and line data assuming [(CO)-C-12]/[(CO)-C-13] = 69 suggests a dust mass for grains with radius
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| 9. |
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| 10. |
- Beutler, A., et al.
(author)
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Adsorption properties of a mixed surface studied by high resolution core level photoemission : CO/0.5 ML Pd/Rh(111)
- 1998
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In: Surface Science. - 0039-6028. ; 411:1-2, s. 111-122
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Journal article (peer-reviewed)abstract
- The coverage-dependent adsorption properties of a laterally heterogeneous bimetallic surface have been investigated by high resolution core level photoemission and low energy electron diffraction. The specific system under study was CO adsorbed on a Rh(111) surface onto which 2D Pd islands (coverage 0.5 ML) were formed by vapor deposition. The CO adsorption properties of the heterogeneous surface were compared with CO adsorption on a Rh(111) surface covered with a full Pd monolayer and with previous results for the CO/Rh(111) system. For low exposures CO is only found on the Rh(111) patches which can be explained by diffusion of CO from the Pd islands onto Rh parts in the adsorption process. At higher exposures CO diffusion from Rh to Pd is indicated. The origin of the diffusion processes can be found in the different coverage-dependent CO adsorption energies on the two surface parts.
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| 11. |
- Beutler, A., et al.
(author)
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Identification of a laterally mobile state during CO adsorption
- 2000
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In: Journal of Physics: Condensed Matter. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 12:6, s. 765-772
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Journal article (peer-reviewed)abstract
- We have investigated CO adsorption at 300 K on ∼ 1.5 atomic layer thick Pd films on a Mo(110) surface by high-resolution core level photoemission. We describe how high-resolution core level spectroscopy may be utilized to study the influence of laterally mobile states on the sticking probability of molecules on such a laterally heterogeneous surface. The present Pd films are laterally heterogeneous in the sense that the additional ∼ 0.5 atomic Pd layer forms mesoscopic one-layer thick islands on top of the first Pd layer. At 300 K, CO chemisorbs on these two-layer thick islands but not on the one-layer parts of the film. The rate at which these two-layer islands are filled by CO molecules as the surface is exposed to CO is found to be consistent with a picture where CO molecules that initially impinge on the one-layer parts of the surface enter a laterally mobile state and diffuse to the two-layer islands and adsorb there. This mobile state is in many respects similar to a classical precursor state.
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| 12. |
- Beutler, A., et al.
(author)
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The influence of preadsorbed oxygen on the adsorption of CO on two-dimensional Pd islands on a Rh (111) surface
- 1998
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In: Surface Science. - 0039-6028. ; 418:2, s. 457-465
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Journal article (peer-reviewed)abstract
- The influence of preadsorbed oxygen on the CO adsorption properties of a laterally heterogeneous bimetallic surface consisting of Pd islands on Rh(111) at a Pd coverage of 0.5 monolayers has been studied by high resolution core level photoemission. A surface consisting of clean Pd islands surrounded by oxygen-covered Rh(111) patches was prepared by predosing oxygen at room temperature. By applying core level photoemission to the Pd 3d5/2 and the C 1s levels, the adsorption of CO on this surface was studied with particular attention being paid to possible CO diffusion between the two surface parts. The CO molecules are found to diffuse from the oxygen-covered Rh(111) patches onto the Pd islands for low to medium CO exposures. This diffusion direction is opposite of that found previously for the 0.5 ML Pd on Rh(111) system with no oxygen predosing. This reversal of the diffusion direction is argued to be due to a large reduction of the CO adsorption energy on the Rh patches of the surface caused by the preadsorbed oxygen.
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| 13. |
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| 14. |
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| 15. |
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| 16. |
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| 17. |
- Sandell, A., et al.
(author)
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Adsorption of acetylene and hydrogen on Pd(111) : Formation of a well-ordered ethylidyne overlayer
- 1998
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In: Surface Science. - 0039-6028. ; 415:3, s. 411-422
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Journal article (peer-reviewed)abstract
- The C2H2(+H)/Pd(111) system has been studied using high resolution core level spectroscopy and low energy electron diffraction (LEED). Two ordered phases were found when adsorbing C2H2 at 125 K, giving rise to a (2 × 2) and a (√3 × √3)R30° LEED pattern, respectively. When preadsorbing H at 110-150 K, the sticking probability of the C2H2 molecules is strongly reduced and only the (√3 × √3)R30° overlayer is formed. In all three of the ordered structures the C2H2 molecules are suggested to occupy the hollow sites. Heating of the (√3 × √3)R30° C2H2 + H layer to 350 K yields a well ordered (√3 × √3)R30° overlayer consisting exclusively of ethylidyne (CCH3) positioned in the hollow sites. The formation of ethylidyne is furthermore found to be preceded by the formation of an intermediate species ("β") which probably is vinylidene.
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| 18. |
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| 19. |
- Sandell, A., et al.
(author)
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Observation of a low-energy adsorbate core-level satellite for CO bonded to palladium : Coordination-dependent effects
- 1998
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In: Physical Review B (Condensed Matter). - 0163-1829. ; 57:20, s. 13199-13208
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Journal article (peer-reviewed)abstract
- A strong low-energy shake-up satellite for CO adsorbed on Pd is observed. The occurrence of the satellite is established for the CO/1 ML Pd/Mo(110) system at a coverage where CO adsorbs exclusively on-top. Comparisons with CO adsorbed on Pd single-crystal surfaces and small supported Pd particles indicate that the strongly increased satellite intensity is due to the decreased CO-Pd interaction strength for on-top adsorbed CO. This can be used to get further insight into the structure and bonding properties of the adsorbate system. Since a low-energy shake-up feature may be misinterpreted as a chemically shifted component, the conclusion is that great care has to be taken in the evaluation of adsorbate core-level spectra for systems with large variations in adsorption strength depending on the adsorbate sites. Large variations in the CO site distribution may furthermore occur depending on the nature of the Pd substrate: Adsorption of CO on 1 ML Pd/Mo(110) leads to an overlayer dominated by an on-top species and, likewise, the CO overlayer formed on small Pd particles after large doses has a large fraction of on-top bonded species. This is in strong contrast to Pd single-crystal surfaces, where CO adsorbed in more highly coordinated sites is abundant.
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| 20. |
- Schaefer, A., et al.
(author)
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Controlled modification of nanoporous gold : Chemical vapor deposition of TiO2 in ultrahigh vacuum
- 2013
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In: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 282, s. 439-443
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Journal article (peer-reviewed)abstract
- TiO2 has been deposited in the first 400 nm of a nanoporous gold (NPG) structure using metal organic chemical vapor deposition with titanium-tetraisopropoxide as single source precursor in ultra high vacuum. The NPG has been pretreated by ozone to clean and stabilize the structure for deposition. The deposited oxide stabilizes the porous structure, otherwise prone to coarsening at elevated temperatures, up to 300 degrees C. The study combines the controlled sample preparation with a functional test of the prepared catalyst under real conditions in a continuous gas flow reactor. The catalytic activity of the loaded NPG at 60 degrees C for CO oxidation is found to be superior to unloaded as-prepared NPG.
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| 21. |
- Schaefer, A, et al.
(author)
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Growth of praseodymium oxide on Si(111) under oxygen-deficient conditions
- 2009
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In: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 80:4, s. 045414-
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Journal article (peer-reviewed)abstract
- Surface science studies of thin praseodymium oxide films grown on silicon substrates are of high interest in view of applications in such different fields as microelectronics and heterogeneous catalysis. In particular, a detailed characterization of the growth and the final structure of the films are mandatory to achieve a fundamental understanding of such topics as oxygen mobility and defect structure, and their role for the electronic and chemical properties. In this paper, the MBE growth of praseodymium oxide films on Si(111) substrates was investigated at low-deposition rates (0.06 nm/min) and low-oxygen partial pressures (p(O-2)<1 x 10(-10) mbar). To obtain insight into the structure and chemical composition of the growing film, spot profile analyzing low-energy electron diffraction (SPA-LEED), transmission electron microscopy, and synchrotron radiation-based x-ray photoelectron spectroscopy (XPS) and x-ray absorption spectroscopy (XAS) were applied. SPA-LEED reveals the formation of an initial closed layer followed by continuous roughening and formation of ordered three-dimensional structures. This result is in contrast to observations at higher-deposition rates, were a layer-by-layer growth was reported. XAS and XPS provide evidence that a continuous reaction takes place in the growing Pr2O3 film leading to the formation of silicate and silicide structures within the film. Combining all data, a consistent picture of the deposition of praseodymium oxide on Si(111) emerges which clearly shows that in contrast to higher-throughput molecular beam epitaxy conditions the reactivity of the growing film strongly influences the growth behavior at low-deposition rates and low pressures.
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| 22. |
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| 23. |
- Wiklund, M, et al.
(author)
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Vibrational fine structure in the C 1s photoemission spectrum of the methoxy species chemisorbed on Cu(100)
- 1998
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In: Surface Science. - 0039-6028. ; 418:1, s. 210-218
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Journal article (peer-reviewed)abstract
- The C 1s photoemission spectrum of methoxy (CH3O) chemisorbed on Cu(100) is demonstrated to contain a resolvable fine structure due to excitation of the molecular C-H normal vibrational mode. The origin of the fine structure is ascertained by substituting hydrogen with deuterium in the methoxy overlayers and by comparison to gas-phase C 1s spectra for methanol (CH3OH). The vibrational fine structure is demonstrated to provide a fingerprint of the hydrocarbon group present on the surface.
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| 24. |
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| 25. |
- Akkurt, I, et al.
(author)
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Photoneutron yields from tungsten in the energy range of the giant dipole resonance
- 2003
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In: Physics in Medicine and Biology. - : IOP Publishing. - 1361-6560 .- 0031-9155. ; 48:20, s. 3345-3352
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Journal article (peer-reviewed)abstract
- Photoneutron production on the nuclei of high-Z components of medical accelerator heads can lead to a significant secondary dose during a course of bremsstrahlung radiotherapy, However, a quantitative evaluation of secondary neutron dose requires improved data on the photoreaction yields. These have been measured as a function of photon energy, neutron energy and neutron angle for W-nat, using tagged photons at the MAX-Lab photonuclear facility in Sweden. This work presents neutron yields for W-nat(gamma, n) and compares these with the predictions of the Monte Carlo code MCNP-GN, developed specifically to simulate photoneutron production at medical accelerators.
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