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- Almanasreh, Hasan, 1981
(författare)
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The Dirac Operator; From Numerics to the Theory of G-convergence
- 2010
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- We consider two main issues concerning the Dirac operator, the first is widely known as the appearance of spurious eigenvalues within the spectrum. The second is the study of the asymptotic behavior of the eigenvalues for a family of Dirac operators with oscillatory potential added to the Coulomb-Dirac Hamiltonian. In the first problem a stable Finite element scheme is used to treat the problem of spuriousity of the radial Dirac operator with a Coulomb potential. The numerical accuracy depends strongly on the derivation of a fine-intrinsic stability parameter. In the second problem we consider the Coulomb-Dirac operator with addition to an abstract oscillating potential. Using the spectral measure of operators we project into the positive part of the perturbed Hamiltonian. By using G-convergence theory of positive self-adjoint operators in Hilbert spaces and ¡- convergence of the associated quadratic functionals we prove G-compactness for a family of positive Dirac operators under certain assumptions on the potentials.
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- Antipov, Sergey V., 1986
(författare)
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Radiative association of C(3 P) and N(4 S) atoms: From semi-classical theory to coupled-states quantum dynamics
- 2010
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the present work formation of the CN radical through radiative association is simulated using both semi-classical and quantum mechanical theories. The rate coefficient for temperatures from 40 K to 1900 K has been computed using the Breit-Wigner theory to account for the resonances. Comparison with the results obtained by the semi-classical method, which completely omits the shape resonances, is accurate to within 25% above room temperature. Furthermore, the role of the spin-orbit and rotational couplings is investigated. Comparison of the energy-dependent rate coefficients calculated with and without spin-orbit and rotational couplings shows that the couplings effect the low-energy part of the rate coefficient.
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- Clemens, Franziska, 1981
(författare)
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Deception Detection and Suspect´s Counter-Interrogation Strategies
- 2010
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Degree of Licentiate in Psychology Abstract Clemens, F. (2010). Deception Detection and Suspects' Counter-Interrogation Strategies. Department of Psychology, University of Gothenburg, Sweden In legal settings correct discriminations between truthful and deceptive statements are of major importance. However, deception detection research shows that lay people, as well as presumed lie experts working within the legal field, rarely achieve accuracy rates above the level of chance. One reason for the low accuracy rates typically found is that differences in behaviour between truth tellers and liars are very subtle, and that there are very few reliable cues to deception. Trying to actively elicit cues to deception (via the Strategic Use of Evidence (SUB) technique) is a new approach that aims at making differences between truth tellers and liars more salient. In the current thesis the SUE-technique is tested for the first time on children acting as mock-suspects (Study 1). In addition, adult suspects' counterinterrogation strategies are investigated (Study 2). Stndy 1 consisted of two experiments. Experiment l focused on the elicitation of diagnostic cues to deception using two types of evidence disclosure techniques (i.e., late evidence disclosure (SUB-technique) vs. early evidence disclosure) when interviewing children (N = 84) who were either guilty or innocent of a mock crime. The results showed that deceptive children omitted significantly more crime-related information than truth-telling children. Furthermore, deceptive children's statements were significantly more inconsistent with the evidence than were the truth-telling children' s statements and this was more pronounced as a function of late compared to early disclosure of evidence. Experiment 2 exarnined to what extent the elicited cues helped receivers (N = 168) to assess the veracity of the children' s statements. The results showed an overall accuracy level of 59.5%, which was significantly above the level of chance. The observers in the late disclosure condition performed better than chance whereas the observers in the early condition did not. However, the difference between these two conditions in terms of accuracy was non-significant. Study 2 investigated guilty mock-suspects' (N = 90) counter-interrogation tactics with respect to the disclosure of possibly self-incriminating information. Specifically, the extent to which the disclosure of this information was moderated by (a) the suspects' criminal experience (nåive vs. experienced), and (b) the degree of suspicion directed towards the suspects (low vs. high). The results showed that experienced (vs. naive) suspects volunteered less self-incriminating information in an initial free recall phase. When asked crime-specific questions, experienced (vs. nåive) suspects admitted having committed less actions fitting with the crime under investigation. Furthermore, experienced suspects' willingness to report information was not affected by the degree of suspicion, whereas nåive suspects in the high-suspicion (vs. low-suspicion) condition were more willing to report information. This thesis presents research that deals with the active elicitation of diagnostic cues to deception by interrogating strategically with respect to the information at hand (Study l), and it exarnines suspects' counter-interrogation strategies (Study 2). Combining these two approaches is important in order to make deception detection assessments more reliable. Keywords: deception detection, interview techniques, strategic use of evidence, counterinterrogation tactics, degree of suspicion, criminal experience, guiIty suspects Franziska Clemens, Department of Psychology, University of Gothenburg, P.O. Box 500, 40530 Gothenburg, Sweden. Phone:+46317861672, E-mail: franziska.clemens@psy.gu.se ISSN 1101-718X ISRN GUIPSYKlA VH--226--SE
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- Cronie, Ottmar, 1979
(författare)
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Different Aspects of Inference for Spatio-Temporal Point Processes
- 2010
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis deals with inference problems related to the Renshaw-Särkkä growth interaction model (RS-model). It is a continuous time spatio-temporal point process with time dependent interacting marks, in which the immigrationdeath process (a continuous time Markov chain) controls the arrivals of new marked points as well as their potential life-times. The data considered are marked point patterns sampled at fixed time points. First we propose three edge correction methods for discretely sampled (marked) spatio-temporal point processes. These are all based on the idea of placing an approximated expected behaviour of our process at hand (based on simulated realisations) outside the study region, which in turn interacts with the data during the estimation. We study the methods and evaluate them numerically in the context of the RS-model. The parameters related to the development of the marks are estimated using the least-squares approach. Secondly, we propose (approximate) maximum likelihood (ML) estimators for the two parameters of the immigration-death process; the arrival intensity and the death rate. The arrival intensity is assumed to be constant and the death rate is assumed to be proportional to a function of the current mark size of a point. The arrival intensity estimator is constructed to compensate for the (unobserved) individuals arriving and dying between two sampled time points. When assumed that the death rate is constant we can derive the transition probabilities of the immigration-death process. These in turn give us the exact likelihood of its parameter pair. We are able to reduce the likelihood maximisation problem from two dimensions to one dimension. Furthermore, under the condition that the parameter pair lies in some compact subset of the positive part of the real plane, we manage to show the consistency and the asymptotic normality of its ML-estimator under an equidistant sampling scheme. These results are also evaluated numerically.
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- Dewrang, Petra
(författare)
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Asperger syndrome: Early signs and slef-perception in adolescents and young adults
- 2010
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Asperger syndrome: Early signs and self-perception in adolescents and young adults. Petra Dewrang Department of Psychology, University of Gothenburg, 2010 ABSTRACT Dewrang, Petra (2010). Asperger syndrome: Early signs and self-perception in adolescents and young adults. Department of Psychology, University of Gothenburg, Sweden. Asperger syndrome (AS) is considered to be a disorder within the autism spectrum and it is in most cases a lifelong disabiIity that affects life in an amount of aspects. It is primarily characterized by impairment in social interaction, restricted patterns of interests and behaviour, speech and language peculiarities, and non-verbal communication problems. In this thesis the overall aim was to investigate the specific behaviours in earl y childhood as assessed retrospectively by the parents and to explore self-perception and self-worth in the adolescents and young adults. The specific purpose of study I was to retrospectively explore the differences between a group of 23 adolescents and young aduIts with Asperger syndrome and a group of 13 typically developing comparison (C) individuals. The groups comprised 14-24-year-olds and the AS group was composed of 19 males and 4 females and the C group of 6 males and 7 females. A parental self-rating questionnaire, Symptoms of Autism Before the Age of 2 (SAB-2) was used and comprised seven fields: Contact and social activity, Responses to sensory perceptions, Communication and language/speech, Food/feeding and sleep, Play and fixations/rituals, Movements and motor skills, and Development and behaviour. An eighth field of possible Rarly suspicions was also a part of the questionnaire. The results showed a significant difference between the AS and the C groups in all the fields, primarily Food/feeding and sleep and Contact and social activity. It was also obvious that many parents were aware ofbehavioural anomalies already in infancy. In study II the specific purpose was to explore how young individuals with AS perceived themselves regarding self-understanding and self-worth compared to a C group of young individuals. The study comprised the same participants as in study I plus three more participants in the AS group and one participant fewer in the C group. The AS group showed lower rates of self-worth on a self-rating questionnaire (the I think I am scale) but not on a conversational interview (the Selfunderstanding interview) which instead revealed qualitatively different self-perceptions. A questionnaire for measuring anxiety/absence of anxiety was also used and showed no differences between the AS and the C groups. Keywords: Asperger syndrome, early diagnosis, parental concern, questionnaire, SAB-2, selfperception, self-understanding, self-worth
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- Eriksson, Frank, 1980
(författare)
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Semiparametric survival models for routine register data
- 2010
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Routine registers offer researchers opportunities to carry out studies of covariate effects on lifetimes of rare diseases otherwise infeasible because of the large cohorts required. Familial relationships necessary for analysis of environmental or genetic factors can be identified by record linking. The vast amount of data and clustering of related individuals pose statistical challenges. As most statistical information is associated with the cases, an estimator based on a sample where cases are overrepresented can drastically reduce the sample size with only a minor loss of efficiency. This thesis concerns regression of clustered cohort sampled survival data within the broad class of semiparametric transformation models. This class includes the proportional hazards and proportional odds models as special cases. Correlations within clusters are modeled by random effects. We derive consistency and asymptotic normality of a weighted maximum likelihood estimator and provide a consistent estimator of its asymptotic variance. A likelihood ratio test for regression coefficients is also proposed. The method is shown to perform well on simulated data and is illustrated by application to a study on cardiovascular diseases among Swedish men.
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