| 1. |
- Arroyo-Torres, B., et al.
(författare)
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VLTI/AMBER studies of the atmospheric structure and fundamental parameters of red giant and supergiant stars
- 2015
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Ingår i: Why Galaxies Care about AGB Stars III: A Closer Look in Space and Time. Proceedings of ASP Conference Series. - 9781583818794 ; 497, s. 91-96
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We present recent near-IR interferometric studies of red giant and supergiant stars, which are aimed at obtaining information on the structure of the atmospheric layers and at constraining the fundamental parameters of these objects. The observed visibilities of the red supergiants (RSGs) and also of one red giant indicate large extensions of the molecular layers, as those previously observed for Mira stars. These extensions are not predicted by hydrostatic PHOENIX model atmospheres, hydrodynamical (RHD) simulations of stellar convection, or self-excited pulsation models. All these models based on parameters of RSGs lead to atmospheric structures that are too compact compared to our observations. We discuss how alternative processes might explain the atmospheric extensions for these objects. As the continuum appears to be largely free of contamination by molecular layers, we can estimate reliable angular Rosseland radii of our stars. Together with distances and bolometric fluxes, we estimate the effective temperatures and luminosities of our targets, locate them in the HR diagram, and compare their positions to recent evolutionary tracks.
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| 2. |
- Bernholt, Andrea, et al.
(författare)
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Profiling School Students' Epistemic Beliefs From Grades 5 to 12
- 2018
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Ingår i: AERA Online Paper Repository. - : American Educational Research Association.
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Konferensbidrag (refereegranskat)abstract
- Individual’s beliefs about the nature of knowing and learning have been investigated under the label of epistemic beliefs. Although the area of epistemic beliefs is still growing, only a few studies deal with school children. A valuable research approach in this area is classifying students in more homogeneous groups according as it is done in Latent Profil Analyses. Therefore, we investigated 3088 secondary students across grades 5 to 12 with LTAs. We found three distinctive profiles (‘sophisticated’, ‘evidence-based/dynamic’, ‘multiplist’) according to students’ science-related epistemic beliefs. As a justification for this approach, results show several differences between these profiles regarding school and background variables, cognitive outcomes in general and in science as well as science related motivational characteristics.
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| 3. |
- Bouziani, I, et al.
(författare)
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Electronic and optical properties of ZnO nanosheet doped and codoped with Be and/or Mg for ultraviolet optoelectronic technologies : density functional calculations
- 2020
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Ingår i: Physica Scripta. - : IOP PUBLISHING LTD. - 0031-8949 .- 1402-4896. ; 95:1
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Tidskriftsartikel (refereegranskat)abstract
- Theoretically, the density functional calculations have been effectuated for investigating electronic and optical properties of zinc oxide nanosheet doped and codoped with Be and/or Mg utilizing the generalized gradient approximation modified Becke-Johnson (GGA-mBJ) approach. The computed results show that the ZnBeO, ZnMgO and ZnBeMgO in nanosheet structure, referring to their low formation energy values, are more stable than those in bulk one. Furthermore, the bandgap of ZnO monolayer can be effectively modulated through substitution of Zn atoms by Be and/or Mg. In addition to that, by incorporating Be and/or Mg, the absorption peaks of ZnO nanosheet shift into the shorter UV-wavelength side as well as its reflectivity becomes lower. These results indicate that doping and codoping process of ZnO monolayer with Be and/or Mg are two efficient ways to modulate electronic and optical properties for ultraviolet optoelectronic technologies.
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| 4. |
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| 5. |
- Hernández Romero, Eulalia, et al.
(författare)
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Integrating weather impact in air traffic controller shift scheduling in remote and conventional towers
- 2022
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Ingår i: EURO Journal on Transportation and Logistics. - : Elsevier. - 2192-4376 .- 2192-4384. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- Weather affects the work of air traffic controllers, however, for staff scheduling in Remote Tower Centers (RTCs) it has not been taken into account. We study the impact of various weather phenomena on air traffic controller (ATCO) taskload through structured interviews with ATCOs. We deduce taskload-driven impact factors and the corresponding thresholds for the intensity of the weather phenomena at several Swedish airports. To account for the uncertainty in the weather prediction, we obtain probabilistic weather data from Ensemble Prediction Systems (EPSs). Then we adjust our prior Mixed Integer Programming (MIP) model for RTC staff scheduling to account for uncertain impactful weather occurrences and yield a distribution for the necessary number of ATCOs for RTC staff scheduling. Our framework can be used for conventional towers as well. We quantify the impact of weather by comparing the number of controllers necessary to operate at five Swedish airports from a remote tower during two example days in 2020, with and without taking weather events into account. In our calculations we use historical weather and flight data to show that ignoring weather impact may lead to significant understaffing at a RTC.
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| 6. |
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| 7. |
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| 8. |
- Nowak, Ethan, 1981-
(författare)
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Complex demonstratives, hidden arguments, and presupposition
- 2021
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Ingår i: Synthese. - : Springer. - 0039-7857 .- 1573-0964. ; 198:4, s. 2865-2900
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Tidskriftsartikel (refereegranskat)abstract
- Standard semantic theories predict that non-deictic readings for complex demonstratives should be much more widely available than they in fact are. If such readings are the result of a lexical ambiguity, as Kaplan (in: Almog, Perry, Wettstein (eds) Themes from Kaplan, Oxford University Press, Oxford, 1977) and others suggest, we should expect them to be available wherever a definite description can be used. The same prediction follows from ‘hidden argument’ theories like the ones described by King (Complex Demonstratives: a Quantificational Account, MIT Press, Cambridge, 2001) and Elbourne (Situations and Individuals, MIT Press, Cambridge, 2005). Wolter (That’s That; the Semantics and Pragmatics of Demonstrative Noun Phrases. Ph.D. thesis, University of California at Santa Cruz, 2006), however, has shown that complex demonstratives admit non-deictic interpretations only when a precise set of structural constrains are met. In this paper, I argue that Wolter’s results, properly understood, upend the philosophical status quo. They fatally undermine the ambiguity theory and demand a fundamental rethinking of the hidden argument approach.
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| 9. |
- Petrov, Kristian, 1975-
(författare)
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Kan ateister fira jul?
- 2015
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Ingår i: SANS. - 1401-8691. ; 5:1, s. 42-46
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 10. |
- Sabelnikov, Vladimir, 1946, et al.
(författare)
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Thin reaction zones in highly turbulent medium
- 2019
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Ingår i: International Journal of Heat and Mass Transfer. - : Elsevier BV. - 0017-9310. ; 128, s. 1201-1205
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Tidskriftsartikel (refereegranskat)abstract
- A big database (23 cases characterized by Damköhler number less than unity) created recently in 3D Direct Numerical Simulation (DNS) of propagation of a statistically one-dimensional and planar, dynamically passive reaction wave in statistically stationary, homogeneous, isotropic turbulence is analyzed. On the one hand, the DNS data well support the classical Damköhler expression, i.e., square-root dependence of a ratio of turbulent and laminar consumption velocities on the turbulent Reynolds number. On the other hand, contrary to the common interpretation of the Damköhler theory and, in particular, to the concept of distributed burning, the DNS data show that the reaction is still localized to thin zones even at D$ as low as 0.01, with the aforementioned ratio of the consumption velocities being mainly controlled by the reaction-zone-surface area. To reconcile these apparently inconsistent numerical findings, an alternative regime of propagation of reaction waves in a highly turbulent medium is analyzed, i.e., propagation of an infinitely thin reaction sheet is theoretically studied, with molecular mixing of the reactant and product being allowed in wide layers. In this limiting case, an increase in the consumption velocity by turbulence is solely controlled by an increase in the reaction-sheet area. Based on physical reasoning and estimates, the area is hypothesized to be close to the mean area of an inert iso-scalar surface at the same turbulent Reynolds number. This hypothesis leads to the aforementioned square-root dependence. Thus, both the DNS data and the developed theory show that a widely accepted hypothesis on penetration of small-scale turbulent eddies into reaction zones is not necessary to obtain the classical Damköhler scaling for turbulent consumption velocity.
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