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| 2. |
- Allende Prieto, C., et al.
(författare)
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Deep SDSS optical spectroscopy of distant halo stars I. Atmospheric parameters and stellar metallicity distribution
- 2014
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Ingår i: Astronomy & Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 568
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Tidskriftsartikel (refereegranskat)abstract
- Aims. We analyze a sample of tens of thousands of spectra of halo turnoff stars, obtained with the optical spectrographs of the Sloan Digital Sky Survey (SDSS), to characterize the stellar halo population "in situ" out to a distance of a few tens of kpc from the Sun. In this paper we describe the derivation of atmospheric parameters. We also derive the overall stellar metallicity distribution based on F-type stars observed as flux calibrators for the Baryonic Oscillations Spectroscopic Survey (ROSS). Methods. Our analysis is based on an automated method that determines the set of parameters of a model atmosphere that reproduces each obserxrci spectrum best. We used an optimization algorithm and evaluate model fluxes by means of inter-polation in a precomputed grid, In our analysis, we account for the spectrograph's varying resolution as a function of fiber and wavelength. Our results for early SDSS (pre-BOSS upgrade) data compare well with those from the SEGUE Stellar Parameter Pipeline (SSPP). except for stars with log g (cgs units) lower than 2.5. Results. An analysis of stars in the globular cluster M 13 reveals a dependence of the inferred metallicity on surface gravity for stars with log g < 2.5, confirming the systematics identified in the comparison with the SSPP. We find that our rnetallicity estimates are, significantly more precise than the SSPP results. We also find excellent agreement with several independent analyses. We show that the SDSS color criteria for selecting F-type halo turnoff stars as flux calibrators efficiently excludes stars with high metallieities, but does not significantly distort the shape of the metallicity distribution at low rnetallicity. We obtain a halo metathcity distribution that is narrower and more asymmetric than in previous studies. The lowest gravity stars in our sample at tens of kpc from the Sun, indicate a shift of the metallicity distribution to lower abundances, consistent with what is expected from a dual halo system in the Milky Way.
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| 3. |
- Ning, Tong, 1975, et al.
(författare)
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MONITORING LONG TERM VARIABILITY IN THE ATMOSPHERICWATER VAPOUR CONTENT USING GROUND-BASED GPS RECEIVER NETWORKS
- 2011
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Ingår i: ESA Proceedings WPP 326 : Proc. 3rd Int. Colloquium – Scientific and Fundamental Aspects of the Galileo Programme.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We have processed 14 years of observations acquiredfrom 33 GPS sites in Sweden and Finland. Estimatedlinear trends in the atmospheric Integrated Water Vapour(IWV), using a 10 degree elevation cutoff angle, are in a range from -0.4 to +0.6 kg/m^2/decade with a typical uncertainty of 0.3–0.4 kg/m^2/decade. The data from 13 GPSsites were processed for 8 different elevation cutoff angles from 5 degree to 40 degree. The resulting IWV trends were compared to the trends obtained from the data acquired at seven nearby radiosonde sites. The results show a clear variation in the trend correlation between the two techniques when different elevation cutoff angles are applied to the GPS data analysis. The best agreement is seen for the 25 degree solution resulting in a correlation coefficient of 0.79.
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| 5. |
- Jannok-Nutti, Ylva
(författare)
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The mathematical knowledge within the sámi culture : a possible base for the mathematics in the sámi schools?
- 2006
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Ingår i: NERA's 34th Congress, Örebro 9-11 March, 2006. - : Nordic educational research association, NERA. ; , s. 76-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The Sámi schools in Sweden follow the national regulations but are profiled after Sámi needs which safeguards and develops the Sámi culture and language. Sámi pupils have to be confident in the Sámi cultural inheritance and they have to be able to speak, read and write Sámi. In accordance with the Sámi schools ordinance there is a need for an education that is aware of and have a base in the Sámi culture. My intention with my research is to describe and try to understand the mathematics from a Sámi point of view. The focus is on the traditional Sámi knowledge and learning. My research questions are following: What is mathematics from a Sámi perspective? Is it possible to connect the education in mathematics in the Sámi schools with the Sámi culture? Is it possible to use the culture as a base for the learning in mathematics? Is it possible to develop a view of teachings in mathematics which act from the Sámi culture?
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| 6. |
- Patrignani, Marco, et al.
(författare)
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Formal Approaches to Secure Compilation : A Survey of Fully Abstract Compilation and Related Work
- 2019
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Ingår i: ACM Computing Surveys. - : Association for Computing Machinery (ACM). - 0360-0300 .- 1557-7341. ; 51:6
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Tidskriftsartikel (refereegranskat)abstract
- Secure compilation is a discipline aimed at developing compilers that preserve the security properties of the source programs they take as input in the target programs they produce as output. This discipline is broad in scope. targeting languages with a variety of features (including objects, higher-order functions, dynamic memory allocation, call/cc, concurrency) and employing a range of different techniques to ensure that source-level security is preserved at the target level. This article provides a survey of the existing literature on formal approaches to secure compilation with a focus on those that prove fully abstract compilation, which has been the criterion adopted by much of the literature thus far. This article then describes the formal techniques employed to prove secure compilation in existing work, introducing relevant terminology, and discussing the merits and limitations of each work. Finally, this article discusses open challenges and possible directions for future work in secure compilation.
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| 8. |
- López-Cordero, Mario
(författare)
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La (des)cortesía en la comunicación mediante ordenador : Los correos electrónicos entre profesor y alumnos
- 2009
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Ingår i: Actas del il congreso de hispanistas y lusitanistas Nordicos. - Estocolmo. ; , s. 43-53
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- En los últimos años, hemos visto cómo las nuevas tecnologías han abierto la posibilidad de comunicarnos de forma nunca vista hasta la irrupción de Internet en nuestras vidas. La comunicación electrónica (chats, correo-e, SMS, MUD), llamada comunicación mediante ordenador, se ha convertido en tan sólo diez años en un medio de masas y ha experimentado un rápido crecimiento. Esto ha hecho que numerosos lingüistas, y otros especialistas, se hayan interesado por estudiar la comunicación en línea. Sin embargo, el estudio de la pragmática y la cortesía lingüística española en entornos virtuales apenas ha sido iniciado (Yus, 2001; Noblia, 2001, 2004; Alcoba Rueda, 2004; Laborda Gil, 2003) y todavía queda mucho por investigar. En nuestro trabajo, se partirá de la teoría de la cortesía lingüística (Brown y Levinson, 1978, 1987) a fin de dilucidar cómo se negocia la imagen social (Goffman, 1967) y cuáles son las estrategias de cortesía en los correos electrónicos entre profesor y alumnos. Esta ponencia contribuirá a profundizar en el conocimiento de la cortesía en entornos virtuales, un área que no ha sido totalmente explorada hasta ahora.
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