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Träfflista för sökning "WFRF:(Carlsen Henrik) ;mspu:(doctoralthesis)"

Sökning: WFRF:(Carlsen Henrik) > Doktorsavhandling

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1.
  • Carlsen, Henrik (författare)
  • Quantal trajectories and geometric phase
  • 1998
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • This thesis concerns the following topics: geometric phase in the context of Galilean invariance and quantum measurements, Rydberg states of hydrogen atoms, vibronic coupling in the E Ä e Jahn-Teller system and realism in quantum computations. In the analyses the de Broglie-Bohm pilot-wave formulation of quantummechanics is mainly used.It is shown that geometric phase is not Galilean invariant. Experimental implications are discussed and it is found that the experiments performed to date are frame independent. An experiment which is in principle able to detect the noninvariance is sketched. By adopting the measurement theory of the pilot-wave formulation it is shown how the measurement induced geometric phase continuously emerges. The Samuel-Bhandari geometric phase is identified as the nonrandom part of the total geometric phase induced in the measurement.Ensembles of particles for a circular Rydberg wave packet are studied. The trajectories of pilot-wave particles are shown to accurately imitate the behaviour of the wave packet in the high quantum number limit. The nonclassical features of the wave packet are intuitively explained by the nonvanishing quantum potential.Vibronic coupling in the Longuet-Higgins model of the E Ä e Jahn-Teller system is investigated by means of quantal trajectories. The pilot-wave picture provides an intuitive tool for discussing time-scales. An argument based on ergodicity leads to an understanding of the averaging procedure over the electronic motion which provides the approximate nuclear motion.The existence of efficient quantum algorithms triggers questions on Natures ability of storing and processing information during quantum computations. The role of elements of reality in quantum computations is addressed using quantal trajectories. It is found that there is a many-to-one relationship between quantal trajectories and performed computations when quantum parallelism is utilized.
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2.
  • Johansson, Henrik, 1965- (författare)
  • Exercise induced breathing problems in adolescents
  • 2015
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Experiencing respiratory symptoms in conjunction with exercise is common in children and adolescents and can have a negative impact on daily life. The aim of the thesis was to estimate the prevalence of exercise-induced dyspnoea, exercise-induced bronchoconstriction (EIB) and exercise-induced laryngeal obstruction (E-ILO) in a general adolescent population, and to explore factors associated with EIB.Methods: All 12-13-year-old adolescents in the city of Uppsala (n=3,838) participated in a survey on exercise-induced dyspnoea. A subsample of adolescents who answered the survey, 103 randomly selected adolescents reporting exercise-induced dyspnoea and 47 random adolescents who did not report exercise-induced dyspnoea underwent standardised treadmill exercise tests for EIB and E-ILO. The exercise test for EIB was performed while breathing dry air; a positive test was defined as a decrease ≥10% in FEV1 from baseline. E-ILO was investigated using continuous laryngoscopy during exercise. Health related quality of life (HRQoL), and objectively measured daily physical activity were investigated in those with (n=49) and without (n=91) a positive EIB-test.Results: The prevalence of exercise-induced dyspnoea was 14%, and the estimated prevalence of EIB and E-ILO in the total population was 19.2% and of 5.7%, respectively, with no gender differences. In adolescents with exercise-induced dyspnoea 40% had EIB, 6% had E-ILO, and 5% had both conditions.An increased baseline level of fraction of nitric oxide in exhaled air (FeNO), female gender, and exercise-induced dyspnoea were associated with a positive EIB test. Female adolescents with EIB had lower HRQoL and lower baseline lung function compared to females without EIB. These differences were not observed in male adolescents. There was no difference in time spent in moderate- to vigorous daily physical activity between adolescents with and without EIB.
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