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| 2. |
- Aires, F., et al.
(författare)
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Microwave hyperspectral measurements for temperature and humidity atmospheric profiling from satellite: The clear-sky case
- 2015
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Ingår i: Journal of Geophysical Research. - 0148-0227 .- 2156-2202 .- 2169-897X .- 2169-8996. ; 120:21, s. 11334-11351
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Tidskriftsartikel (refereegranskat)abstract
- This study investigates the benefits of a satellite HYperspectral Microwave Sensor (HYMS) for the retrieval of atmospheric temperature and humidity profiles, in the context of numerical weather prediction (NWP). In the infrared, hyperspectral instruments have already improved the accuracy of NWP forecasts. Microwave instruments so far only provide observations for a limited number of carefully selected channels. An information content analysis is conducted here to assess the impact of hyperspectral microwave measurements on the retrieval of temperature and water vapor profiles under clear-sky conditions. It uses radiative transfer simulations over a large variety of atmospheric situations. It accounts for realistic observation (instrument and radiative transfer) noise and for a priori information assumptions compatible with NWP practices. The estimated retrieval performance of the HYMS instrument is compared to those of the microwave instruments to be deployed on board the future generation of European operational meteorological satellites (MetOp-SG). The results confirm the positive impact of a HYMS instrument on the atmospheric profiling capabilities compared to MetOp-SG. Temperature retrieval uncertainty, compared to a priori information, is reduced by 2 to 10%, depending on the atmospheric height, and improvement rates are much higher than what will be obtained with MetOp-SG. For humidity sounding these improvements can reach 30%, a significant benefit as compared to MetOp-SG results especially below 250 hPa. The results are not very sensitive to the instrument noise, under our assumptions. The main impact provided by the hyperspectral information originates from the higher resolution in the O2 band around 60 GHz. The results are presented over ocean at nadir, but similar conclusions are obtained for other incidence angles and over land. Key Points A hyperspectral MW instrument could improve temperature & humidity retrieval compared to MetOp-SG The main impact from HYMS comes from higher resolution in the O2 band around 60 GHz Hyperspectral information is not really sensitive to instrument noise.
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| 3. |
- Charlton, J. E., et al.
(författare)
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A sub-millimetre wave airborne demonstrator for the observation of precipitation and ice clouds
- 2010
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Ingår i: International Geoscience and Remote Sensing Symposium (IGARSS). - Piscataway, NJ : IEEE Communications Society. - 9781424433940 ; , s. 1023-1026
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Konferensbidrag (refereegranskat)abstract
- Sub-millimetre remote sensing instruments can provide critical information on cirrus clouds and an alternative way of measuring precipitation with a much smaller antenna than those which microwave sensors currently use. Two satellite concepts CIWSIR and GOMAS were proposed as ESA Earth Explorer missions; these were not funded, however they were recommended for an aircraft demonstrator. ESA studies have been performed to identify the optimum instrument and platform to demonstrate these satellite concepts. This paper reports on one of these preparatory activities; the design of a sub-millimetre wave airborne demonstrator for both ice cloud and precipitation observations which will be able to prove the feasibility of the scientific principles of both satellite missions. The paper will describe the derivation of the demonstrator requirements, consideration of the available platform and instrument options, the design of the selected concept, performance prediction and the outline of a proof of concept flight campaign. It will present the outcome of the study which describes a demonstrator design based upon the new Met Office International Sub-Millimetre Airborne Radiometer (ISMAR).
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| 4. |
- Chen, Z. H., et al.
(författare)
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The Hydrogen-poor Superluminous Supernovae from the Zwicky Transient Facility Phase I Survey. I. Light Curves and Measurements
- 2023
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 943:1
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Tidskriftsartikel (refereegranskat)abstract
- During the Zwicky Transient Facility (ZTF) Phase I operations, 78 hydrogen-poor superluminous supernovae (SLSNe-I) were discovered in less than 3 yr, constituting the largest sample from a single survey. This paper (Paper I) presents the data, including the optical/UV light curves and classification spectra, while Paper II in this series will focus on the detailed analysis of the light curves and modeling. Our photometry is primarily taken by ZTF in the g, r, and i bands, and with additional data from other ground-based facilities and Swift. The events of our sample cover a redshift range of z = 0.06 − 0.67, with a median and 1σ error (16% and 84% percentiles) of zmed=0.265. The peak luminosity covers −22.8 mag ≤ Mg,peak ≤ −19.8 mag, with a median value of -21.48. The light curves evolve slowly with a mean rest-frame rise time of trise = 41.9 ± 17.8 days. The luminosity and timescale distributions suggest that low-luminosity SLSNe-I with a peak luminosity ∼−20 mag or extremely fast-rising events (<10 days) exist, but are rare. We confirm previous findings that slowly rising SLSNe-I also tend to fade slowly. The rest-frame color and temperature evolution show large scatters, suggesting that the SLSN-I population may have diverse spectral energy distributions. The peak rest-frame color shows a moderate correlation with the peak absolute magnitude, i.e., brighter SLSNe-I tend to have bluer colors. With optical and UV photometry, we construct the bolometric luminosity and derive a bolometric correction relation that is generally applicable for converting g, r-band photometry to the bolometric luminosity for SLSNe-I.
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| 5. |
- Kangas, Heli, et al.
(författare)
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3D Printing High-Consistency Enzymatic Nanocellulose Obtained from a Soda-Ethanol-O2 Pine Sawdust Pulp.
- 2019
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Ingår i: Bioengineering (Basel, Switzerland). - : MDPI AG. - 2306-5354. ; 6:3
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Tidskriftsartikel (refereegranskat)abstract
- Soda-ethanol pulps, prepared from a forestry residue pine sawdust, were treated according to high-consistency enzymatic fibrillation technology to manufacture nanocellulose. The obtained nanocellulose was characterized and used as ink for three-dimensional (3D) printing of various structures. It was also tested for its moisture sorption capacity and cytotoxicity, as preliminary tests for evaluating its suitability for wound dressing and similar applications. During the high-consistency enzymatic treatment it was found that only the treatment of the O2-delignified pine pulp resulted in fibrillation into nano-scale. For 3D printing trials, the material needed to be fluidized further. By 3D printing, it was possible to fabricate various structures from the high-consistency enzymatic nanocellulose. However, the water sorption capacity of the structures was lower than previously seen with porous nanocellulose structures, indicating that further optimization of the material is needed. The material was found not to be cytotoxic, thus showing potential as material, e.g., for wound dressings and for printing tissue models.
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| 7. |
- Kangas, Tuomas, et al.
(författare)
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The morphology of the ejecta of SN 1987A at 31 yr from 1150 to 10 000 angstrom
- 2022
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 511:2, s. 2977-2993
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Tidskriftsartikel (refereegranskat)abstract
- We present spectroscopy of the ejecta of SN 1987A in 2017 and 2018 from the Hubble Space Telescope and the Very Large Telescope, covering the wavelength range between 1150 and 10000 angstrom. At 31 yr, this is the first epoch with coverage over the ultraviolet-to-near-infrared range since 1995. We create velocity maps of the ejecta in the H alpha, Mg II lambda lambda 2796, 2804 and [OI] lambda lambda 6302, 6366 (vacuum) emission lines and study their morphology. All three lines have a similar morphology, but Mg II is blueshifted by similar to 1000 km s(-1) relative to the others and stronger in the north-west. We also study the evolution of the line fluxes, finding a brightening by a factor of similar to 9 since 1999 in Mg II, while the other line fluxes are similar in 1999 and 2018. We discuss implications for the power sources of emission lines at late times: thermal excitation due to heating by the X-rays from the ejecta-ring interaction is found to dominate the ultraviolet Mg II lines, while the infrared Mg II doublet is powered mainly by Ly alpha fluorescence. The X-ray deposition is calculated based on merger models of SN 1987A. Far-ultraviolet emission lines of H-2 are not detected. Finally, we examine the combined spectrum of recently discovered hotspots outside the equatorial ring. Their unresolved Balmer emission lines close to zero velocity are consistent with the interaction of fast ejecta and a clumpy, slowly moving outflow. A clump of emission in this spectrum, south of the equatorial ring at similar to 1500 km s(-1), is likely associated with the reverse shock.
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| 8. |
- Kvaerner, A. S., et al.
(författare)
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The CRCbiome study: a large prospective cohort study examining the role of lifestyle and the gut microbiome in colorectal cancer screening participants
- 2021
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Ingår i: Bmc Cancer. - : Springer Science and Business Media LLC. - 1471-2407. ; 21:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Colorectal cancer (CRC) screening reduces CRC incidence and mortality. However, current screening methods are either hampered by invasiveness or suboptimal performance, limiting their effectiveness as primary screening methods. To aid in the development of a non-invasive screening test with improved sensitivity and specificity, we have initiated a prospective biomarker study (CRCbiome), nested within a large randomized CRC screening trial in Norway. We aim to develop a microbiome-based classification algorithm to identify advanced colorectal lesions in screening participants testing positive for an immunochemical fecal occult blood test (FIT). We will also examine interactions with host factors, diet, lifestyle and prescription drugs. The prospective nature of the study also enables the analysis of changes in the gut microbiome following the removal of precancerous lesions. Methods: The CRCbiome study recruits participants enrolled in the Bowel Cancer Screening in Norway (BCSN) study, a randomized trial initiated in 2012 comparing once-only sigmoidoscopy to repeated biennial FIT, where women and men aged 50-74 years at study entry are invited to participate. Since 2017, participants randomized to FIT screening with a positive test result have been invited to join the CRCbiome study. Self-reported diet, lifestyle and demographic data are collected prior to colonoscopy after the positive FIT-test (baseline). Screening data, including colonoscopy findings are obtained from the BCSN database. Fecal samples for gut microbiome analyses are collected both before and 2 and 12 months after colonoscopy. Samples are analyzed using metagenome sequencing, with taxonomy profiles, and gene and pathway content as primary measures. CRCbiome data will also be linked to national registries to obtain information on prescription histories and cancer relevant outcomes occurring during the 10 year follow-up period. Discussion: The CRCbiome study will increase our understanding of how the gut microbiome, in combination with lifestyle and environmental factors, influences the early stages of colorectal carcinogenesis. This knowledge will be crucial to develop microbiome-based screening tools for CRC. By evaluating biomarker performance in a screening setting, using samples from the target population, the generalizability of the findings to future screening cohorts is likely to be high.
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| 9. |
- Leloudas, G., et al.
(författare)
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The superluminous transient ASASSN-15lh as a tidal disruption event from a Kerr black hole
- 2016
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Ingår i: Nature Astronomy. - : Springer Science and Business Media LLC. - 2397-3366. ; 1:1
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Tidskriftsartikel (refereegranskat)abstract
- When a star passes within the tidal radius of a supermassive black hole, it will be torn apart1. For a star with the mass of the Sun (M-circle dot) and a non-spinning black hole with a mass <10(8)M(circle dot), the tidal radius lies outside the black hole event horizon2 and the disruption results in a luminous flare(3-6). Here we report observations over a period of ten months of a transient, hitherto interpreted(7) as a superluminous supernova(8). Our data show that the transient rebrightened substantially in the ultraviolet and that the spectrum went through three different spectroscopic phases without ever becoming nebular. Our observations are more consistent with a tidal disruption event than a superluminous supernova because of the temperature evolution(6), the presence of highly ionized CNO gas in the line of sight(9) and our improved localization of the transient in the nucleus of a passive galaxy, where the presence of massive stars is highly unlikely(10,11). While the supermassive black hole has a mass >10(8)M(circle dot)(12,13), a star with the same mass as the Sun could be disrupted outside the event horizon if the black hole were spinning rapidly(14). The rapid spin and high black hole mass can explain the high luminosity of this event.
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| 10. |
- Mikola, M., et al.
(författare)
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Liquid-Liquid Equilibria for the n-Pentyl acetate, n-Hexyl acetate, n-Pentanol, or n-Hexanol + Furfural + Water Systems at 298 and 323 K
- 2021
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Ingår i: Journal of Chemical and Engineering Data. - : American Chemical Society. - 0021-9568 .- 1520-5134. ; 66:1, s. 210-221
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Tidskriftsartikel (refereegranskat)abstract
- In this study, four ternary liquid-liquid equilibrium systems containing a solvent, furfural, and water were investigated by performing liquid-liquid equilibrium measurements at two different temperatures. The solvents were n-pentyl acetate, n-hexyl acetate, n-pentanol, and n-hexanol. The measurements were compared to the literature data and modeled with the UNIQUAC (universal quasi-chemical) activity coefficient model by taking into account also the vapor-liquid, liquid-liquid, and vapor-liquid-liquid equilibrium behaviors if present. n-Hexyl acetate showed the smallest solubility in water both in binary and ternary measurements. All four ternary systems showed similar magnitude distribution coefficients but furfural had the highest selectivity to n-hexyl acetate. Among the four systems investigated in this work, n-hexyl acetate was observed to have the best characteristics as a solvent for the extraction of furfural from water. © 2020 American Chemical Society.
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