The solar wind has an important impact on the Earth and its magnetic field. Among the solar wind perturbations, there can be jumps in the solar wind dynamic pressure as well as strong magnetic excursions in the z-component of the Interplanetary Magnetic Field (IMF B_(Z )). When coronal mass ejections and other solar disturbances take place in the solar wind, there can be clear changes in the global geomagnetic field, as measured by a magnetic index called Sym-H. In this thesis some unusual events were found for which there were large fluctuations either in the solar wind dynamic pressure or in the IMF B_Z but not simultaneously in both. These events suggest that the response of the geomagnetic field to the dynamic pressure fluctuations of the solar wind is variable. In particular, it was found that the earthward component (x-component) of the IMF appeared to influence the magnitude of the Sym-H response. By contrast, there was no visible impact of the y-component of the IMF. In a second exceptional event it was found that the IMF was changing substantially while the solar wind dynamic pressure remained very constant. From this study a time delay between the IMF B_Z component and the resulting Sym-H was found to be of the order of 60 to 90 minutes.

Ο όρος μη-γραμμική οπτική αντιπροσωπεύει τον κλάδο της οπτικής ο οποίος μελετά την αλληλεπίδραση της ύλης με ακτινοβολία πολύ ισχυρής έντασης. Όταν ένα υλικό εκτεθεί σε ακτινοβολία υψηλής έντασης όπως αυτή του laser, οι οπτικές του ιδιότητες αλλάζουν εξαιτίας της πόλωσης που επάγεται στα δομικά υλικά του και το αποτέλεσμα είναι η αλλαγή των οπτικών του ιδιοτήτων. Αυτό με τη σειρά του οδηγεί σε μια πληθώρα φαινομένων τα οποία μας βοηθούν στη κατανόηση της δομής του υλικού αλλά και των φυσικών μηχανισμών που κρύβονται πίσω από αυτά. Στην παρούσα μεταπτυχιακή εργασία μελετώνται οι μη γραμμικές οπτικές ιδιότητες χρωμοφόρων τύπου BODIPY υπό μορφή διαλυμάτων. Η σύνθεση των μορίων έγινε στο Ινστιτούτο Φυσικοχημείας του ΕΚΕΦΕ ΔΗΜΟΚΡΙΤΟΣ από την ερευνητική ομάδα του κ.Πιστόλη στα πλαίσια ενός έργου ΘΑΛΛΗ. Η διάρθωση της εργασίας είναι η εξής: Στο πρώτο κεφάλαιο γίνεται μια εισαγωγή και παρουσιάζονται κάποιες βασικές έννοιες της μη γραμμικής οπτικής. Ενώ ταυτόχρονα αναπτύσσονται αναλυτικότερα μερικά φαινόμενα τα οποία οφείλονται στη μη γραμμική επιδεκτικότητα τρίτης τάξης. Στο δεύτερο κεφάλαιο γίνεται η παρουσίαση της πειραματικής τεχνικής Z-scan, που χρησιμοποιήθηκε για τη διεξαγωγή των πειραμάτων, αλλά και η διαδικασία που ακολουθήθηκε για την εξαγωγή των μη γραμμικών οπτικών ιδιοτήτων από τα πειραματικά δεδομένα. Στο τρίτο κεφάλαιο παρουσιάζονται τα πειραματικά αποτελέσματα των συστημάτων που μελετήθηκαν. Αρχικά, παρουσιάζεται μια περιγραφή των ιδιαίτερων φωτοφυσικών ιδιοτήτων των μορίων BODIPY που μελετήθηκαν. 'Επειτα, ακολουθεί η μη γραμμική οπτική απόκριση των συστημάτων για διέγερση στα 532nm και 1064nm με παλμούς χρονικής διάρκειας 532ps και 4ns. Τέλος, ακολουθούν τα συμπεράσματα από τη μελέτη των συστημάτων και μια πρόταση για μελλοντική μελέτη. / Nonlinear optics (NLO) is related to laser-matter interactions, as well as the changes which are induced in materials during their interaction with intense laser fields. Laser beams can provide strong enough electromagnetic fields, capable of inducing optical changes. In these cases the response of the material is not linearly dependent on the intensity of the electric field. The primary objective of this thesis was the investigation of the non-linear optical properties of BODIPY derivatives. In particular, we focused on the determination of the second-order hyperpolarizability in order to correlate the magnitude and the sign of the observed nonlinearities with their photophysical characteristics. The main experimental technique used was the Z-scan technique, employing 35 ps and 4 ns laser pulses at both 532 nm and 1064 nm. The molecules were synthesized by the research group of Dr. Pistolis at the Institute of Physical Chemistry NCSR ''Demokritos" as a part of the ''THALIS" programme. The structure of the thesis is as follows: In Chapter 1, the basic NLO phenomena and the corresponding related nonlinear optical parameters are introduced. In Chapter 2, the theoretical background of the Z-scan technique is briefly presented, while the Z-scan experimental set-up is fully described. In Chapter 3, experimental results on the NLO properties of the Bodipy derivatives are presented. The relationship between the nonlinear optical properties and photophysical properties of the derivatives is also considered. The conclusion summarizes the results of the NLO response of the BODIPY derivatives and details a proposal for future work..

Note: / Karol Szymanowski's music has fascinated me for a long time. The first time I encountered his name was in Artur Rubinstein's autobiography, which recounts how they first met and narrates many anecdotes about their friendship. At the time, I was living in Brazil, and was unable to find any recordings of his music. Nonetheless, Rubinstein's ardent praise of him (“a master!”, “a great Polish composer!”, “a powerful, original personality”) made me very curious, and I did not abandon my desire to keep looking for his music. Then, when I moved to Montreal in order to start my undergraduate degree at McGill University, I was finally able to find many recordings of his works at the school's library.[...]

Bakgrund: Många företag går i konkurs varje år vilket leder till att olika intressenter drabbas hårt till följd av konkursen. Därmed har konkursprognostiseringsmodeller utvecklats för att ge en tidig varning till intressenterna om företags framtida finansiella kris.  I Sverige använder kreditinstituten sig av sina egna modeller för att förutspå konkurser, dessa modeller är inte publicerade för allmänheten. I och med detta är vi intresserade att tillämpa utländska modeller på den svenska marknaden. Syfte: Syftet med denna uppsats är att undersöka fyra internationella prognostiseringsmodeller för att analysera hur tillämpbara de är på den svenska marknaden. Metod: Undersökningen har baserats på en kvantitativ forskningsstrategi och en deduktiv forskningsansats. Urvalet grundades på de företag som inlett konkurs år 2012 samt en kontrollgrupp bestående av friska företag. Slutligen bestod det slumpmässiga urvalet av 31 konkursföretag och 31 friska företag som tillhör tillverknings- och industribranschen. Teori: Under teoriavsnittet beskrivs de modeller som används i denna studieforskning. Vidare redogörs för nyckeltalens betydelse vid bedömning av företags finansiella förhållanden. Slutligen beskrivs tidigare forskning inom konkursprognostisering. Resultat och slutsats: Modellerna är inte tillämpbara på den svenska tillverknings- och industribranschen då dessa inte har presenterat tillförlitliga resultat på vår studie. Vi anser att en vidare revidering av dessa modeller behövs för att dessa ska kunna tillämpas på den svenska marknaden.

Significance tests for the measure of raw agreement are proposed. First, it is shown that the measure of raw agreement can be expressed as a proportionate reduction-in-error measure, sharing this characteristic with Cohen's Kappa and Brennan and Prediger's Kappa_n. Second, it is shown that the coefficient of raw agreement is linearly related to Brennan and Prediger's Kappa_n. Therefore, using the same base model for the estimation of expected cell frequencies as Brennan and Prediger's Kappa_n, one can devise significance tests for the measure of raw agreement. Two tests are proposed. The first uses Stouffer's Z, a probability pooler. The second test is the binomial test. A data example analyzes the agreement between two psychiatrists' diagnoses. The covariance structure of the agreement cells in a rater by rater table is described. Simulation studies show the performance and power functions of the test statistics. (author's abstract) / Series: Research Report Series / Department of Statistics and Mathematics

This master thesis examines the development of the two earlier independent IR protocols Z39.50 and SR (Search and Retrieve, ISO 10162/10163), now Z39.50/SR, from the beginning of the 80s to 1996 and their functionality in the client/server environment. Z39.50 applications in library systems will allow easy access to information regardless of platform or location. The use of Z39.50 will create a new user environment. Almost all the library systems of the market support the Z39.50 and surprisingly the use of it in Sweden lied on a very low leve! in 1996. This thesis was followed-up by an interview and a questioner among the Swedish Z39.50 users. They could see a huge potential of development concerning the future IR process. Z39.50 will change the libraries' traditional IR structure and the behaviour of the end-users.

L'écriture de spécifications pour des logiciels en général et en particulier pour des applications sécurisées demande de développer des techniques qui facilitent la détection et la prévention des erreurs de conception, dès les premières phases du développement. Ce besoin est motivé par les coûts et délais des phases de vérification et validation. De nombreuses méthodes de spécification, tant formelles qu'informelles ont été proposées et, comme nous le verrons dans cette thèse, les approches formelles donnent des spécifications de meilleure qualité.L'ingénierie des systèmes sécurisés propose l'utilisation de modèles de conception de la sécurité pour représenter les applications sécurisées. Dans de nombreux cas, ces modèles se basent sur les notations graphiques d'UML avec des extensions, sous forme de profils comme SecureUML, pour exprimer la sécurité. Néanmoins, les notations d'UML, même étendues avec des assertions OCL, sont insuffisantes pour garantir la correction de ces modèles. Ceci est notamment du aux limites des outils d'animation utilisés pour valider des modèles UML étendus en OCL. Nous proposons de combiner des langages formels comme Z avec UML pour valider des applications en animant leurs spécifications, indépendamment de futurs choix d'implémentation. Le but de cette thèse est de présenter une approche pour analyser par animation des modèles de conception de la sécurité. Nous utilisons un outil pré-existant, RoZ, pour traduire les aspects fonctionnels du modèle UML en Z. Cependant, RoZ ne couvre pas la modélisation des aspects sécuritaires. Dans cette thèse, nous avons complété l'outil RoZ en l'associant à un noyau de sécurité qui spécifie les concepts du modèle RBAC (Role Based Access Control). Nous utilisons l'animation pour explorer dynamiquement et ainsi valider les aspects sécuritaires de l'application.Notre approche et les outils qui la supportent intègrent UML, SecureUML (un langage de modélisation de la sécurité), RBAC, RoZ, Z et Jaza, un animateur pour le langage Z. L'animation des spécifications prend la forme de scénarios définis par l'utilisateur qui permettent de se convaincre que la spécification décrit correctement ses besoins. Notre approche permet une validation dès la phase de spécification, qui prend en considération l'interaction entre les modèles fonctionnel et sécuritaire, et qui fait abstraction des choix de l'implémentation. Les éléments du modèle fonctionnel peuvent être utilisés comme contexte dans la définition des permissions du modèle de sécurité. Notre approche ne met pas de contrainte sur ce modèle fonctionnel ce qui permet de l'utiliser pour une vaste gamme d'applications.

Although higher correlation between gauge and radar at hourly or daily accumulations are reported, it is rarely observed at higher time resolution (e.g. 10 -minute). This study investigates six major rainfall events in year 2000 in the greater Winnipeg area with durations varying from four to nine hours. The correlation between gauge and radar measurements of precipitation is found to be only 0.3 at 10-minute resolution and 0.55 at hourly resolution using Marshall-Palmer’s Z-R relationship (Z=200R1.6). The rainfalls are classified into convective and stratiform regions using Steiner et al. (1995)’s algorithm and two different Z-R relationships are tested to minimize the error associated with the variability of drop-size-distribution, however no improvement is observed. The performance of the artificial neural network is explored as a reflectivity-rainfall mapping function. Three different types of neural networks are explored: the back propagation network, the radial basis function network, and the generalized regression neural network. It is observed that the neural network’s performance is better than the Z-R relationship to estimate the rainfall events which was used for training and validation (correlation 0.67). When this network is tested on a new rainfall its performance is found quite similar to that obtained from the Z-R relationship (correlation 0.33). Based on this observation neural network may be recommended as a post-processing tool but may not be very useful for operational purposes - at least as used in this study. Variability in weather and precipitation scenarios affects the radar measurements which apparently makes it impossible for the neural network or the Z-R relationship to show consistent performance at every rainfall event. To account for variability in weather and rainfall scenarios conventional correction schemes for attenuation and hail contamination are applied and a trajectory model is developed to account for rainfall advection due to wind drift. The trajectory model uses velocity obtained from the single-doppler observation. A space-time interpolation technique is applied to generate reflectivity maps at one-minute resolution based on the direction obtained from the correlation based tracking algorithm. The trajectory model uses the generated reflectivity maps having one-minute resolution which help to account for the travel time by the rainfall mass to reach to the ground. It was found that the attenuation correction algorithm adversely increases the reflectivity. This study assumes that the higher reflectivity caused by hail contaminated regions is one reason for the overestimation in the attenuation correction process. It was observed that the hail capping method applied prior to the attenuation correction algorithm helps to improve the situation. A statistical expression to account for radome attenuation is also developed. It is observed that the correlation between the gauge and the radar measurement is 0.81 after applying the various algorithms. Although Marshall-Palmer’s relationship is recommended for stratiform precipitation only, this study found it suitable for both convective and stratiform precipitation when attenuation is properly taken into account. The precipitation processing model developed in this study generates more accurate rainfall estimates at the surface from radar observations and may be a better choice for rainfall-runoff modellers.

We construct geometric models for K-homology with coefficients based on the theory of Z/k-manifolds. To do so, we generalize the operations and relations Baum and Douglas put on spinc-manifolds to spinc Z/kZ-manifolds. We then de fine a model for K-homology with coefficients in Z/k using cycles of the form ((Q,P), (E,F), f) where (Q, P) is a spinc Z/k-manifold, (E, F) is a Z/k-vector bundle over (Q, P) and f is a continuous map from (Q, P) into the space whose K-homology we are modelling. Using results of Rosenberg and Schochet, we then construct an analytic model for K-homology with coefficients in Z/k and a natural map from our geometric model to this analytic model. We show that this map is an isomorphism in the case of finite CW-complexes. Finally, using direct limits, we produced geometric models for K-homology with coefficients in any countable abelian group.

This thesis describes an analysis of the process e⁺e^— → l⁺l^- (where l = e, μ,, τ) at centre-of-mass energies between 88 GeV and 94 GeV, using the data collected by the DELPHI detector between the years 1991 and 1993. The leptonic decays of the Z° boson are selected without attempting to separate the three lepton types, thus making it an inclusive lepton analysis. The theory behind lepton pair production is introduced and the extraction of various electroweak parameters from the experimental observables is discussed. The LEP collider and the DELPHI detector are described, with special emphasis being given to the sub-detectors used in the analysis. The criteria used to select a high purity leptonic sample are described along with calculations of various backgrounds and efficiencies. The sample of selected leptonic events is then used to measure the cross-sections and forward-backward asymmetries. Finally, a fit to these cross-sections and asymmetries, together with the hadronic (e⁺e^- → qq̄) cross-sections, is carried out. Various Z° parameters are obtained: the mass and total width Mz-91.1876 ± 0.0052 GeV/c², Γ_z = 2.4971 ± 0.0061 GeV, the ratio of the hadronic to leptonic partial widths R_l = 20.73 ± 0.09, and the pole leptonic asymmetry (A°_FB)¹ = 0.0195 ± 0.0042. Using these results and the value of the strong coupling constant (α_s), determined by the DELPHI collaboration, the number of light neutrino species is determined to be N_ν = 3.045 ± 0.035. The leptonic partial width is found to be: Γ_l = 83.82 ± 0.29 MeV. Using the measured leptonic forward-backward asymmetries, the squared vector and axial-vector couplings of the Z° to charged leptons are found to be (ĝ_v¹)^{2</sup = (1.65 ± 0.36) x 10^-3 and (ĝ_a¹)}2</sup> = 0.2505 ± 0.0009. These values can be used to determine the effective rho parameter and the effective weak mixing angle: p̂ = 1.0020 ± 0.0036, and sin² θ^eff_lept = 0.2297 ± 0.0024. A full Standard Model fit to the data gives the values of the strong coupling constant, α_s, and the mass of the top quark, m_top, as being: α_s = 0.123 ± 0.010, m_top = 178⁺²²_-25 (expt)<sup>+18<sup>_-16(Higg s)GeV/c², where 60 < m_Higgs (GeV/c²) < 1000 with a central value of 300 GeV/c². All the results obtained agree with the results from the lepton-identified analyses (analyses in which leptonic events are selected on the basis of their individual flavour) and with the predictions of the Standard Model.