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Modelling coexisting GSF and shear instabilities in rotating stars
No full textZahn's widely used model for turbulent mixing induced by rotational shear has recently been validated (with some caveats) in non-rotating shear flows. It is not clear, however, whether his model remains valid in the presence of rotation, even though this was its original purpose. Furthermore, new instabilities arise in rotating fluids, such as the Goldreich-Schubert-Fricke (GSF) instability. Which instability dominates when more than one can be excited, and how they influence each other, were open questions that this paper answers. To do so, we use direct numerical simulations of diffusive stratified shear flows in a rotating triply periodic Cartesian domain located at the equator of a star. We find that either the GSF instability or the shear instability tends to take over the other in controlling the system, suggesting that stellar evolution models only need to have a mixing prescription for each individual instability, together with a criterion to determine which one dominates. However, we also find that it is not always easy to predict which instability 'wins' for given input parameters, because the diffusive shear instability is subcritical, and only takes place if there is a finite-amplitude turbulence 'primer' to seed it. Interestingly, we find that the GSF instability can in some cases play the role of this primer, thereby providing a pathway to excite the subcritical shear instability. This can also drive relaxation oscillations, which may be observable. We conclude by proposing a new model for mixing in the equatorial regions of stellar radiative zones due to differential rotation. © 2021 The Author(s).Immediate accessThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]
High-Energy Neutrino Flux Studied in the ANTARES Deep-Sea Telescope
No full textHigh-energy neutrinos from cosmic origin appear to be ideal probes for long-distance astronomy and may provide insight into cosmic particle acceleration mechanisms. The ANTARES deep-sea neutrino telescope, fully operational since May 2008, aims at the detection of upgoing muon tracks caused by high energy neutrinos having passed through the Earth. Stringent limits have been set on the sensitivity to neutrino point sources and a diffuse neutrino flux for the Southern sky.</p
Towards a Precise Measurement of Atomic Parity Violation in a Single Ra+ Ion
No full textIn the singly charged Ra+ ion the contributions of the weak interactions to the atomic level energies are some 50 times larger than in the Cs atom. We report the results of laser spectroscopy experiments on Ra-209-214(+) isotopes in preparation of a precision atomic parity violation experiment. Experimental input data is provided for testing the atomic theory, which is necessary for a competitive extraction of the Weinberg angle at low energies.</p
Application of the Gaussian sum filter to magnetic field localization for achieving both accurate and efficient estimates in the case of multimodality
No full textMagnetometers are widely equipped in smartphones. They measure the direction and the magnitude of the magnetic field of the environment. Since the measurements are not transition data, there is no drift when estimating position and orientation using a magnetometer. Furthermore, magnetic field localization using magnetometers requires no extra devices set in the environment, and this indicates the cost of localization using a magnetometer can be lower than other localization methods that need multiple devices set in the localizing area. Therefore, magnetic field localization is an interesting method for indoor localization. However, there exists a research gap in the algorithms that have been applied to magnetic field localization. In the current research, the Extended Kalman filter (EKF) and the Particle filter (PF) are applied to magnetic field localization. The EKF is more efficient than the PF, but has low accuracy when the distribution is multimodal. On the other hand, the PF is more computationally costly compared to the EKF but is more robust to the multimodality. As a result, a survey of the possible solutions to the current research gap was carried out. From this survey, Gaussian sum filter (GSF) was found to be a promising candidate as the solution to the research gap. To test the performance and assumptions of the GSF, the GSF was applied to a fully simulated magnetic field localization system and a localization system with the measurements obtained from a real-world magnetometer. The results from these simulations show that the GSF is more suitable for multimodality than the EKF. Besides, the computational cost of the GSF is found to be lower than the PF while the GSF has an equivalent or even better accuracy than the PF.Mechanical Engineering | Systems and Contro
High-Energy Neutrino Flux Studied in the ANTARES Deep-Sea Telescope
No full textHigh-energy neutrinos from cosmic origin appear to be ideal probes for long-distance astronomy and may provide insight into cosmic particle acceleration mechanisms. The ANTARES deep-sea neutrino telescope, fully operational since May 2008, aims at the detection of upgoing muon tracks caused by high energy neutrinos having passed through the Earth. Stringent limits have been set on the sensitivity to neutrino point sources and a diffuse neutrino flux for the Southern sky
Literaturdokumentation zum Thema ''Waldschaeden'' 3. Fortfuehrung. Stand: Maerz 1993
No full textThis GSF report is the third continuation of the already published literature documentation of July 1986. In addition to the roughly 4500 papers included up to the second continuation in the documentation, another 1500 entries have been included, processed by computer and made into this volume. The indicated literature is kept in the archives of PBWU, where it is accessible to readers and can be lent out. Furthermore, computer-aided literature searches are conducted on request, as hitherto. The third continutation again contains a list of descriptors with the code numbers of the papers in question. An author index was additonally made up, permitting retrieval of entries by co-author names. For each paper entered, the following information is given: Consecutive number, name of author, title, bibliographic source, key words (drecriptors). The subjects of the international literature recorded cover the entire range of forest decline research including land pollution, atmospheric pollution and pollution of rivers and lakes, aerial photograph analyses, plant physiological data, forest damage surveys, climate factors, liming and fertilization experiments, etc. (orig./UWA)Der vorliegende GSF-Bericht stellt die 3. Fortfuehrung der veroeffentlichten Literaturdokumentationen vom Juli 1986 dar. Inzwischen wurden zu den bis zur 2. Fortfuehrung aufgenommenen rund 4500 Zitaten weitere 1500 gesammelt, rechnergestuetzt bearbeitet und nun als 3. Fortfuehrung bibliographisch zusammengestellt. Die zitierte Literatur ist im Archiv der PBWU vorhanden und kann eingesehen oder ausgeliehen werden. Darueber hinaus koennen wie bisher auf Anfrage rechnergestuetzte Literaturrecherchen durchgefuehrt werden. Auch in der 3. Fortfuehrung befindet sich im Anhang ein ''Deskriptorenverzeichnis'' mit Nummernzuordnung zu den aufgenommenen Literaturzitaten. Zusaetzlich wurde ein Autorenverzeichnis angelegt, welches das Aufsuchen auch zweit- oder folgend genannter Autoren anhand der Literaturzitat-Nummern ermoeglicht. Die Darstellung umfasst jeweils: - Laufende Nummer; - Autor; - Titel; - Quellenangabe; -Schlagwoerter (Deskriptoren). Thematisch ist internationale Literatur aus dem gesamten Spektrum der Waldschadensforschung inkl. Boden-, Luft-, Gewaesserverschmutzung, Luftbildanalysen, pflanzenphysiologische Daten, Forstliche Schadenserhebungen, Klimafaktoren, Duengungs- u. Kalkumosversuche etc. erfasst. (orig./UWA)Available from TIB Hannover: RO 2674(1993,23) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBayerisches Staatsministerium fuer Landesentwicklung und Umweltfragen, Muenchen (Germany)DEGerman
Towards a Precise Measurement of Atomic Parity Violation in a Single Ra+ Ion
No full textIn the singly charged Ra+ ion the contributions of the weak interactions to the atomic level energies are some 50 times larger than in the Cs atom. We report the results of laser spectroscopy experiments on Ra-209-214(+) isotopes in preparation of a precision atomic parity violation experiment. Experimental input data is provided for testing the atomic theory, which is necessary for a competitive extraction of the Weinberg angle at low energies
Hollins Columns (1980 Nov 24)
Get PDFTable of Contents: GSF hosts feminist author Greer Committee updates presidential search White gift marks start of Christmas season Brevity of vacation still calendar issue CMC stresses availability Mock, real vote contrasts sharp, Commentary Woodrow Wilson Visiting Fellows discuss current women\u27s issues Anorexics have FAT self image Independent exam system depends on student honesty Poets discuss Frost\u27s life, work Husband-wife team finds Hollins ideal situation Works in Progress combines student-teacher talents Roanoke Plasma Co. questionable but clean Crosby finishes teaching career Consumer tips offer Area merchants offer Christmas gift ideas Roanoke plans varied holiday events Basketball Schedule Soccer ends with win More than Bats And Blackness Hot Spots offer W&L alternative In search of... Midnight munchieshttps://digitalcommons.hollins.edu/newspapers/2130/thumbnail.jp
Narrativa autobiográfica de um imigrante nos EUA: um estudo de caso pelo viés da Gramática Sistêmico-Funcional
No full textThis is a case study which aims to analyze the autobiographical representations made by a Mexican immigrant in the US, Richard Rodriguez, of his identity and social inclusion processes, while being educated in the English language. Specifically, we focus on the lexicogrammatical choices made, regarding the participants, processes and circumstances that background his social identity construction within the family (Spanish) and public (English) contexts, in addition to the historically-situated discursive practices that underlie the transition between his two worlds and will help to build up the new self. Besides, we also shed light on those social actors whose roles played during the narrator´s assimilation process were considered to be relevant by the author. Excerpts which we judged to be the most relevant to represent the writer´s views were taken from the corpus - made up of a prologue and six chapters - and analyzed based on the Halliday & Matthiessen´s ideational metafunction, whose meaning is realized through the Transitivity System in the Systemic-Functional Grammar (GSF). The GSF was chosen because it focuses on the relation between language and other aspects of the social life, while the choice for the present corpus was made on the basis that it is canonical in the USA in the treatment of questions related to immigrants´ assimilation process in America and education in a second language. The analysis of the social actors is carried out according to Van Leeuwen´s (2003) theory of Representation of Social Actors, which has also proved to be especially useful in getting an understanding of the roles played by all involved in the narrative. We also analyze the meanings created by the narrator ( semantic strata of the GSF ) which come from his lexicogramatical choices mentioned above, basing the analysis on the theories devised by scholars such as Fairclough (1992,2003), Giddens (2002), Castells (2008), de Fina (2003, 2006), and Edwards (2006), among others. The analysis above leads us to the conclusion that, in the writer´s views, it is essential for the immigrant to give up his culture and language in order to fully assimilate the new culture. Therefore, he places himself against the government´s bilingual program by claiming it to be a hindrance to the whole assimilation process. We also come to prove right the claim that the subject does not exist prior to language, without which he would not come to be and recognize himself as an individual in the society. Finally, we tried to show how useful and efficient an instrument of research GSF can be to analyze the individual´s representations of his experiences and his world, making us co-participants in the ideologies defended before all the society.Este é um estudo de caso que busca analisar as representações que um imigrante mexicano nos EUA, Richard Rodriguez, faz de seu processo de construção identitária e inclusão social no país, durante sua educação na língua inglesa, através da narrativa autobiográfica. Especificamente, analisamos as escolhas léxico-gramaticais de participantes, processos e circunstâncias envolvidos na construção de sua identidade social nos contextos familiar (espanhol) e público (inglês), além das práticas discursivas historicamente específicas, que embasam a transição entre esses dois contextos e que irão determinar o novo sujeito. Ainda, focalizamos os atores sociais, participantes que assumem papéis relevantes durante essa transição e posterior assimilação pelo narrador. As escolhas léxico-gramaticais são analisadas utilizando-se recortes do corpus - Hunger of Memory - The Education of Richard Rodriguez - que melhor ilustram as experiências do autor durante o processo de construção da identidade americana, tendo por base a metafunção ideacional, cujo significado é realizado pelo sistema de transitividade, da Gramática Sistêmico-Funcional (GSF) de Halliday (2004). A escolha pela teoria da GSF ocorre por ser a mesma uma gramática voltada para a relação da linguagem com outros elementos e aspectos da vida social. A escolha do corpus, uma autobiografia composta por um prólogo e seis capítulos, resulta do fato do livro de Richard constituir uma obra canônica nos EUA, no tratamento das questões da imigração e educação numa segunda língua. A análise dos atores sociais baseia-se na teoria da representação dos atores sociais de Van Leeuwen (2008), a qual constitui, assim como a GSF, um instrumento bastante eficaz na busca da compreensão dos papéis desempenhados tanto por nosso protagonista quanto por todos aqueles representados na narrativa. Procedemos a uma terceira análise, semântico-discursiva, com base nas teorias de pensadores como Fairclough (1992,2003), Giddens (2002), Castells (2008), De Fina (2003, 2006) e Edwards (2006), dentre outros. A análise do corpus nos faz concluir que, na visão do autor, é preciso que o imigrante se afaste de sua cultura e de sua língua para poder assimilar completamente a nova cultura. O autor se coloca, também, contrário ao programa de bilingualismo proposto pelo governo americano, afirmando ser esse um entrave ao processo de assimilação no país de destino e ao aprendizado do novo idioma. Confirmamos, ainda, a teoria de que o sujeito não pré-existe à língua e que, sem ela, é impossível se reconhecer e se situar como indivíduo na sociedade. Por fim, tentamos mostrar como a GSF pode ser instrumento útil e eficaz na análise de representações que o sujeito faz de suas experiências e de seu mundo, colocando-nos como co-participantes de suas ideologias defendidas perante a sociedade como um todo
Narrativa autobiográfica de um imigrante nos EUA: um estudo de caso pelo viés da Gramática Sistêmico-Funcional
Get PDFThis is a case study which aims to analyze the autobiographical representations made by a Mexican immigrant in the US, Richard Rodriguez, of his identity and social inclusion processes, while being educated in the English language. Specifically, we focus on the lexicogrammatical choices made, regarding the participants, processes and circumstances that background his social identity construction within the family (Spanish) and public (English) contexts, in addition to the historically-situated discursive practices that underlie the transition between his two worlds and will help to build up the new self. Besides, we also shed light on those social actors whose roles played during the narrator´s assimilation process were considered to be relevant by the author. Excerpts which we judged to be the most relevant to represent the writer´s views were taken from the corpus - made up of a prologue and six chapters - and analyzed based on the Halliday & Matthiessen´s ideational metafunction, whose meaning is realized through the Transitivity System in the Systemic-Functional Grammar (GSF). The GSF was chosen because it focuses on the relation between language and other aspects of the social life, while the choice for the present corpus was made on the basis that it is canonical in the USA in the treatment of questions related to immigrants´ assimilation process in America and education in a second language. The analysis of the social actors is carried out according to Van Leeuwen´s (2003) theory of Representation of Social Actors, which has also proved to be especially useful in getting an understanding of the roles played by all involved in the narrative. We also analyze the meanings created by the narrator ( semantic strata of the GSF ) which come from his lexicogramatical choices mentioned above, basing the analysis on the theories devised by scholars such as Fairclough (1992,2003), Giddens (2002), Castells (2008), de Fina (2003, 2006), and Edwards (2006), among others. The analysis above leads us to the conclusion that, in the writer´s views, it is essential for the immigrant to give up his culture and language in order to fully assimilate the new culture. Therefore, he places himself against the government´s bilingual program by claiming it to be a hindrance to the whole assimilation process. We also come to prove right the claim that the subject does not exist prior to language, without which he would not come to be and recognize himself as an individual in the society. Finally, we tried to show how useful and efficient an instrument of research GSF can be to analyze the individual´s representations of his experiences and his world, making us co-participants in the ideologies defended before all the society.Este é um estudo de caso que busca analisar as representações que um imigrante mexicano nos EUA, Richard Rodriguez, faz de seu processo de construção identitária e inclusão social no país, durante sua educação na língua inglesa, através da narrativa autobiográfica. Especificamente, analisamos as escolhas léxico-gramaticais de participantes, processos e circunstâncias envolvidos na construção de sua identidade social nos contextos familiar (espanhol) e público (inglês), além das práticas discursivas historicamente específicas, que embasam a transição entre esses dois contextos e que irão determinar o novo sujeito. Ainda, focalizamos os atores sociais, participantes que assumem papéis relevantes durante essa transição e posterior assimilação pelo narrador. As escolhas léxico-gramaticais são analisadas utilizando-se recortes do corpus - Hunger of Memory - The Education of Richard Rodriguez - que melhor ilustram as experiências do autor durante o processo de construção da identidade americana, tendo por base a metafunção ideacional, cujo significado é realizado pelo sistema de transitividade, da Gramática Sistêmico-Funcional (GSF) de Halliday (2004). A escolha pela teoria da GSF ocorre por ser a mesma uma gramática voltada para a relação da linguagem com outros elementos e aspectos da vida social. A escolha do corpus, uma autobiografia composta por um prólogo e seis capítulos, resulta do fato do livro de Richard constituir uma obra canônica nos EUA, no tratamento das questões da imigração e educação numa segunda língua. A análise dos atores sociais baseia-se na teoria da representação dos atores sociais de Van Leeuwen (2008), a qual constitui, assim como a GSF, um instrumento bastante eficaz na busca da compreensão dos papéis desempenhados tanto por nosso protagonista quanto por todos aqueles representados na narrativa. Procedemos a uma terceira análise, semântico-discursiva, com base nas teorias de pensadores como Fairclough (1992,2003), Giddens (2002), Castells (2008), De Fina (2003, 2006) e Edwards (2006), dentre outros. A análise do corpus nos faz concluir que, na visão do autor, é preciso que o imigrante se afaste de sua cultura e de sua língua para poder assimilar completamente a nova cultura. O autor se coloca, também, contrário ao programa de bilingualismo proposto pelo governo americano, afirmando ser esse um entrave ao processo de assimilação no país de destino e ao aprendizado do novo idioma. Confirmamos, ainda, a teoria de que o sujeito não pré-existe à língua e que, sem ela, é impossível se reconhecer e se situar como indivíduo na sociedade. Por fim, tentamos mostrar como a GSF pode ser instrumento útil e eficaz na análise de representações que o sujeito faz de suas experiências e de seu mundo, colocando-nos como co-participantes de suas ideologias defendidas perante a sociedade como um todo
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