| 501. |
- Guenther, E. W., et al.
(författare)
-
A new mass and radius determination of the ultra-short period planet K2-106b and the fluffy planet K2-106c
- 2024
-
Ingår i: Monthly Notices of the Royal Astronomical Society. - 0035-8711 .- 1365-2966. ; 529:1, s. 141-154
-
Tidskriftsartikel (refereegranskat)abstract
- Ultra-short period planets (USPs) have orbital periods of less than 1 d. Since their masses and radii can be determined to a higher precision than long-period planets, they are the preferred targets to determine the density of planets which constrains their composition. The K2-106 system is particularly interesting because it contains two planets of nearly identical masses. One is a high-density USP, the other is a low-density planet that has an orbital period of 13 d. Combining the Gaia DR3 results with new ESPRESSO data allows us to determine the masses and radii of the two planets more precisely than before. We find that the USP K2-106 b has a density consistent with an Earth-like composition, and K2-106 c is a low-density planet that presumably has an extended atmosphere. We measure a radius of R p = 1 . 676 + 0 . 037 -0 . 037 R ⊕, a mass of M p = 7 . 80 + 0 . 71 -0 . 70 M ⊕, and a density of ρ= 9 . 09 + 0 . 98 -0 . 98 g cm -3 for K2-106 b. For K2-106 c, we derive R p = 2 . 84 + 0 . 10 -0 . 08 R ⊕, M p = 7 . 3 + 2 . 5 -2 . 4 M ⊕, and a density of ρ= 1 . 72 + 0 . 66 -0 . 58 g cm -3 . We finally discuss the possible structures of the two planets with respect to other low-mass planets.
|
|
| 502. |
- Gumaelius, Lena, et al.
(författare)
-
Outreach initiatives operated by universities for increasing interest in science and technology
- 2016
-
Ingår i: European Journal of Engineering Education. - : Taylor & Francis Group. - 0304-3797 .- 1469-5898. ; , s. 1-34
-
Tidskriftsartikel (refereegranskat)abstract
- Since the 1990s, the low number of students choosing to study science and technology in higher education has been on the societal agenda and many initiatives have been launched to promote awareness regarding career options. The initiatives particularly focus on increasing enrolment in the engineering programmes. This article describes and compares eight European initiatives that have been established and operated by universities (and in some cases through collaboration with other actors in society). Each initiative is summarised in a short essay that discusses motivation, organisation, pedagogical approach, and activities. The initiatives are characterised by comparing the driving forces behind their creation, how the initiative activities relate to the activities at the university, size based on the number of participants and cost per participant and pedagogical framework. There seem to be two main tracks for building outreach activities, one where outreach activities are based on the university's normal activities, and one where outreach activities are designed specifically for the visiting students.
|
|
| 503. |
- Gunnarsson, Anders, 1981, et al.
(författare)
-
Kinetics of Ligand Binding to Membrane Receptors from Equilibrium Fluctuation Analysis of Single Binding Events
- 2011
-
Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 1520-5126 .- 0002-7863. ; 133:38, s. 14852-14855
-
Tidskriftsartikel (refereegranskat)abstract
- Equilibrium fluctuation analysis of single binding events has been used to extract binding kinetics of ligand interactions with cell-membrane bound receptors. Time-dependent total internal reflection fluorescence (TIRF) imaging was used to extract residence-time statistics of fluorescently stained liposomes derived directly from cell membranes upon their binding to surface-immobilized antibody fragments. The dissociation rate constants for two pharmaceutical relevant antibodies directed against different B-cell expressed membrane proteins was clearly discriminated, and the affinity of the interaction could be determined by inhibiting the interaction with increasing concentrations of soluble antibodies. The single-molecule sensitivity made the analysis possible without overexpressed membrane proteins, which makes the assay attractive in early drug-screening applications.
|
|
| 504. |
- Gunnarsson, Adrian, 1990, et al.
(författare)
-
Radiative Heat Transfer Modeling and in Situ Diagnostics of Soot in an 80 kWth Propane Flame with Varying Feed-Gas Oxygen Concentration
- 2018
-
Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 1520-5045 .- 0888-5885. ; 57:36, s. 12288-12295
-
Tidskriftsartikel (refereegranskat)abstract
- This work presents experimental measurements of various 80 kWth propane flames, using a swirl burner, and modeling of the radiative heat transfer. The combustion conditions were altered by varying the oxygen concentration in the oxidant within range of 21-32%, while keeping the thermal input and oxygen-to-fuel ratio constant. Temperature, gas composition, and radiative intensity were measured using probes, while the soot volume fraction was quantified using nonintrusive laser-induced incandescence. The radiative intensity and the soot volume fraction increased with an increased oxygen concentration in the flame. When the oxygen concentration exceeded 27% the soot volume fraction was increased more than 14-fold. The results reveal the potential of promoting radiative heat transfer by increasing the oxygen concentration; the total radiative intensity becomes dominated by the soot particle contribution. In addition, laser-induced incandescence was successfully used for instantaneous and spatially resolved soot measurements in this type of furnace being at a technical scale.
|
|
| 505. |
- Gunnarsson, Maria, 1987, et al.
(författare)
-
Direct Evidence for Reaction between Cellulose and CO2 from Nuclear Magnetic Resonance
- 2021
-
Ingår i: ACS Sustainable Chemistry and Engineering. - : AMER CHEMICAL SOC. - 2168-0485. ; 9:42, s. 14006-14011
-
Tidskriftsartikel (refereegranskat)abstract
- The direct reaction between carbohydrates and CO2 has recently attracted attention in the context of cellulose dissolution and derivatization as well as carbon capture applications. We have directly demonstrated the formation of cellulose carbonate upon the introduction of CO2 into a non-aqueous cellulose solution by nuclear magnetic resonance spectroscopy. Comparison of the observed spectra with accurate electronic structure calculations of the changes in chemical shifts upon reaction allowed us to confirm the expectation that CO2 reacts with the hydroxyl group on carbon 6 of the cellulose but not exclusively this hydroxyl group. We found good agreement between predicted and measured chemical shifts using a simple computational method.
|
|
| 506. |
- Guo, Xiaoxian, et al.
(författare)
-
Understand the genomic diversity and evolution of fungal pathogen Candida glabrata by genome-wide analysis of genetic variations
- 2020
-
Ingår i: Methods. - : Elsevier BV. - 1095-9130 .- 1046-2023. ; 176, s. 82-90
-
Tidskriftsartikel (refereegranskat)abstract
- The yeast Candida glabrata, an opportunistic human fungal pathogen, is the second most prevalent cause of candidiasis worldwide, with an infection incidence that has been increasing in the past decades. The completion of the C. glabrata reference genome made fundamental contributions to the understanding of the molecular basis of its pathogenic phenotypes. However, knowledge of genome-wide genetic variations among C. glabrata strains is limited. In this study, we present a population genomic study of C. glabrata based on whole genome re-sequencing of 47 clinical strains to an average coverage of ∼63×. Abundant genetic variations were identified in these strains, including single nucleotide polymorphisms (SNPs), small insertion/deletions (indels) and copy number variations (CNVs). The observed patterns of variations revealed clear population structure of these strains. Using population genetic tests, we detected fast evolution of several genes involved in C. glabrata adherence ability, such as EPA9 and EPA10. We also located genome structural variations, including aneuploidies and large fragment CNVs, in regions that are functionally related to virulence. Subtelometric regions were hotspots of CNVs, which may contribute to variation in expression of adhesin genes that are important for virulence. We further conducted a genome-wide association study that identified two SNPs in the 5′UTR region of CST6 that were associated with fluconazole susceptibility. These observations provide convincing evidence for the highly dynamic nature of the C. glabrata genome with potential adaptive evolution to clinical environments, and offer valuable resources for investigating the mechanisms underlying drug resistance and virulence in this fungal pathogen. (249 words)
|
|
| 507. |
- Gustafson, Carl, et al.
(författare)
-
Modeling the cluster decay in mm-wave channels
- 2014
-
Ingår i: 8th European Conference on Antennas and Propagation, EuCAP 2014. - 9788890701849 ; , s. 803-807
-
Konferensbidrag (refereegranskat)abstract
- © 2014 European Association on Antennas and Propagation.The cluster power is an important parameter for cluster-based wireless channel models. This paper addresses modeling and estimation of the cluster power for wireless channels. A novel way of estimating the cluster decay and cluster fading, where the effects of the noise floor is taken into account, is presented. Due to the noise floor present in the measurement, only a limited number of clusters are available when estimating the cluster decay. It is shown that the estimated cluster decay and cluster fading can be improved if the effects of the noise floor and cluster fading are modeled and taken into account in the estimation step. If the noise floor is not taken into account in the estimation of the cluster decay, the resulting model can overestimate the RMS delay spread. Further, the paper includes estimates of the cluster decay and fading based on measured clusters for an indoor wireless mm-Wave channel in a conference room environment.
|
|
| 508. |
- Gustafson, Carl, et al.
(författare)
-
Modeling the Polarimetric mm-wave Propagation Channel using Censored Measurements
- 2016
-
Ingår i: Proceedings - IEEE Global Communications Conference, GLOBECOM. - 2334-0983 .- 2576-6813. - 9781509013289 ; , s. Article number 7842003-
-
Konferensbidrag (refereegranskat)abstract
- This paper presents results based on polarimetric radio channel measurements at 60 GHz in a small room and in an empty, unfurnished, medium-sized room. The measurements in the small meeting room were performed using dual-polarized virtual antenna array elements at both the transmitter and receiver sides and includes LOS and NLOS scenarios. In the unfurnished room, a directional horn antenna was scanned in the azimuth plane and the Rx antenna was an omnidirectional antenna. Based on these measurements, the paper presents experimental parameter estimates for a novel model of the polarimetric propagation paths, that includes the power-decay as well as a correlated fading for the different polarization components. This work also includes an estimation method that takes measurement limitations caused by the noise floor and the limited cross-polarization discrimination of the antennas into account using censored samples.
|
|
| 509. |
- Gustafson, Carl, et al.
(författare)
-
Statistical Modeling and Estimation of Censored Pathloss Data
- 2015
-
Ingår i: IEEE Wireless Communications Letters. - 2162-2337 .- 2162-2345. ; 4:5, s. 569-572
-
Tidskriftsartikel (refereegranskat)abstract
- Pathloss is typically modeled using a log-distance power law with a large-scale fading term that is log-normal. However, the received signal is affected by the dynamic range and noise floor of the measurement system used to sound the channel, which can cause measurement samples to be truncated or censored. If the information about the censored samples is not included in the estimation method, as in ordinary least squares estimation, it can result in biased estimation of both the pathloss exponent and the large scale fading. This can be solved by applying a Tobit maximum-likelihood estimator, which provides consistent estimates for the pathloss parameters. This letter provides information about the Tobit maximum-likelihood estimator and its asymptotic variance under certain conditions.
|
|
| 510. |
- Gustafson, Johan, et al.
(författare)
-
High-energy surface X-ray diffraction for fast surface structure determination
- 2014
-
Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 343:6172, s. 758-761
-
Tidskriftsartikel (refereegranskat)abstract
- Understanding the interaction between surfaces and their surroundings is crucial in many materials-science fields such as catalysis, corrosion, and thin-film electronics, but existing characterization methods have not been capable of fully determining the structure of surfaces during dynamic processes, such as catalytic reactions, in a reasonable time frame. We demonstrate an x-ray-diffraction–based characterization method that uses high-energy photons (85 kiloelectron volts) to provide unexpected gains in data acquisition speed by several orders of magnitude and enables structural determinations of surfaces on time scales suitable for in situ studies. We illustrate the potential of high-energy surface x-ray diffraction by determining the structure of a Pd surface in situ during catalytic CO oxidation and follow dynamic restructuring of the surface with subsecond time resolution.
|
|
