On étudie les propriétés de spin des états évanescents d'un semi-conducteur dépourvu de centre d'inversion. La topologie particulière des bandes évanescentes qui résulte de l'interaction spin-orbite est à l'origine d'un l'effet tunnel anormal. La nature même du processus tunnel devient très dépendante de l'orientation cristallographique de la barrière. Deux cas typiques sont analysés : tunneling sous incidence oblique sur une barrière orientée selon la direction [001] et tunneling sous incidence normale au travers d'une barrière orientée dans la direction [110]. Dans le premier cas, un processus tunnel quasi-classique peut être restauré de façon assez subtile et des effets de filtres à spin sont mis en évidence. Dans le second cas, la situation est particulièrement originale. La notion de courant de probabilité, qui joue un rôle central, est réexaminée et les conditions de discontinuité aux interface de la dérivée de la fonction d'onde sont établies. Selon cette direction où la levée de dégénérescence de spin de la bande de conduction est maximum, il n'y a curieusement aucun filtrage de spin mais l'onde transmise subit un déphasage dont le signe dépend de l'orientation du spin. On prédit des effets de précession de spin autour d'un champ effectif complexe régnant dans la barrière. Ces résultats permettent de concevoir, par ingénierie spin-orbite d'hétérostructures, des dispositifs tunnel résonnant capables de manipuler le spin.

The Edmonton Drug Treatment and Community Restoration Court (EDTC) diverts substance-addicted offenders from the criminal justice system and provides intensive court supervision, case management, and links to social, employment and education support. This thesis aimed to generate a grounded theory of the process of participant engagement with the EDTC, drawing on staff and participant interviews and observation of EDTC operations. Criteria of engagement included meeting expectations, communicating openly and honestly, and forming bonds. Internal engagement was described as feeling hopeful and willing, and perceiving expectations as helpful rather than controlling. Perceptions underlying internal engagement involved motivation and openness to socialization and trust; feeling engaged resulting in the act of confronting issues rather than avoiding them. The process of engagement was a positive cycle, instigated and perpetuated through interaction with expectations and discipline, realizing and experiencing specific reasons to change, forming trust and accessing internal and external resources to address barriers.

The activity of glutamate transporters is essential for the temporal and spatial regulation of the neurotransmitter concentration in the synaptic cleft which is critical for proper neuronal signaling. Because of their role in controlling extracellular glutamate concentrations, dysfunctional glutamate transporters have been implicated in several neurodegenerative diseases and psychiatric disorders. Therefore, investigating the mechanism of substrate transport by these transporters is essential in understanding their behavior when they malfunction. A bacterial glutamate transporter homologue has been successfully crystallized revealing the molecular architecture of glutamate transporters. However, many important questions remain unanswered. In this thesis, I will address the role of D439 in the binding of Na+, and I will identify other electrogenic steps that contribute to the total electrogenicity of the transporter cycle. The role of D439 in the binding of Na+ to the transporter was explored previously in this lab. While it was proposed that the effect of D439 in Na+ binding is indirect, the results described in this thesis provides added support to this work. Here, I will show that the D439 mutation changed the pharmacology of EAAC1 such that THA was converted from a transported substrate to a competitive inhibitor. I will also show that Na+ binding to the substrate-bound mutant transporter occurred with the same affinity as that of Na+ to the substrate-bound wild-type transporter. Therefore, based on these results, D439 is not directly involved in the binding of Na+ to the substrate-bound transporter, but that its effect is rather indirect through changing the substrate binding properties. Na+ binding steps to the empty transporter and to the glutamate-bound EAAC1 contribute only 20% of the total electrogenicity of the glutamate transporter reactions cycle. While K+-induced relocation has been proposed to be electrogenic, there is no experimental evidence that supports it. In this work, I will show that the K+-induced relocation of the empty transporter is electrogenic. Moreover, the results in this work show that the K+-dependent steps are slower than the steps associated with the Na+/glutamate translocation suggesting that the K+-induced relocation determines the transporter?s properties at steady state.

A model of a three species intraguild predation community is proposed. The model is realized as a system of cross-diffusion equations which allow the intraguild prey species to adjust its motility based on local resource and intraguild predator densities. Solutions to the cross-diffusion system are shown to exist globally in time and the existence of a global attractor is proved. Abstract permanence theory is used to study conditions for coexistence in the ecological community. The case where the intraguild prey disperses randomly is compared to the case where the intraguild prey disperses conditionally on local ecological fitness and it is shown that the ability of the intraguild prey to persist in the ecological community is enhanced if the intraguild prey utilizes a movement strategy of avoiding areas with negative fitness. A finite element scheme is used to numerically simulate solutions to the system and confirm the analytical results.

Business profits constitute the main part of income derived through international business and these profits are only to be taxed in the home state of the enterprise. However, if the enterprise conducts business in a host state through a PE, the profits attributable to the PE are taxable in the host state. Article 7 of the OECD Model Tax determines the profits attributable to the PE. Nevertheless, Member States have interpreted Article 7 of the OECD Model Tax Convention in various ways. In order to provide consensus the OECD adopted an authorised OECD approach for attributing profits to PEs. The first part of the purpose of this thesis is to study the Swedish approach for attributing profits to dependent agent PEs in relation to the authorised OECD approach. An enterprise from the home state can be considered to have a dependent agent PE in the host state if it conducts business in the host state through a dependent agent located therein. This is provided that the agent has the authority to conclude contracts in the name of the enterprise and exercises this authority regularly. Under the authorised OECD approach for profit attribution to dependent agent PEs it is possible to allocate profits to the PE in excess of the arm’s length remuneration paid to the dependent agent. Thereby, the OECD has adopted the dual taxpayer approach as the authorised OECD approach. According to the author’s opinion the Swedish perspective regarding profit attribution to dependent agent PEs differs from the authorised OECD approach as the dual taxpayer approach so far has not been applied in Sweden. Furthermore, it differs as the attribution of capital to PEs is not allowed according to case law and as far as the recognition of internal dealings is concerned. When the OECD adopted the dual taxpayer approach as the authorised OECD approach another method was available; the single taxpayer approach. In line with this approach no further profits in excess of the arm’s length remuneration to the dependent agent can be attributed to the dependent agent PE. However, the single taxpayer approach was rejected as the authorised OECD approach, which has lead to disagreement within the international tax community. Therefore, the second part of the purpose of this thesis is to study to what extent the authorised OECD approach is sustained. This is done by analysing reactions to the single and dual taxpayer approach among business and academic circles. The author believes that reactions against the dual taxpayer approach mainly arise in situations when an enterprise in the host state gives rise to a dependent agent PE. Therefore, the authorised OECD approach should have recognised that different types of dependent agent PEs might arise and the approach is only sustained to the extent that a person belonging to the foreign enterprise leads to the existence of a dependent agent PE.

Alzheimer’s disease has increasing effects on the Swedish population. Now, about 90 000 swedes have been diagnosed with the disease. Many of these persons are cared for by someone close to them. The aim of this study is to increase understanding for the situation and experiences of the persons caring for their affected partner and to examine which support they are given by the public sector. It is a qualitative case study where four persons have been interviewed. Previous research concerning experiences, coping strategies and the need for aid is used for reference. The theories chosen for the aim of the study is coping strategies, role theory, social interaction, informal care and informal aid. The results show that the participants have had different experiences of caring for their partners of which stress, anxiety and seeing it as a burden was common. The participants had different coping abilities to master their different situations and over all had good coping strategies. Their need for aid was different but all participants stressed that there is need for support and that this need to be developed. The following conclusions can be drawn from the study. The experiences are different depending on the individual case. It is important for those active within the line of social care to have knowledge about coping strategies in order to give support to those providing care for their kin. All participants experienced a lack of cooperation and information. / Alzheimers sjukdom drabbar Sveriges befolkning i allt större utsträckning. Ungefär 90 000 personer i Sverige har diagnosen. Många av dessa personer vårdas av någon i sin omgivning. Syftet med studien är att få en ökad förståelse för partners som vårdar sin respektive som har Alzheimers sjukdom och vilka upplevelser som förekommer samt att undersöka hur stödet från samhället ser ut. Det är en kvalitativ fallstudie där intervjuer har gjorts med fyra personer. Tidigare forskning har tagits fram som berör upplevelser, olika copingstrategier och behov av stöd. De teorier som valdes för studiens ändamål är copingstrategier, rollteori, social integration, informell omsorg och informell hjälp. Resultatet visar att deltagarna hade olika upplevelser av att vårda varav stress, oro och börda var vanligt. Deltagarna hade olika copingförmågor för att bemästra de olika situationerna och det förekom överlag goda copingstrategier. Behovet av stöd såg olika ut, men deltagarna belyste att det fanns ett behov av stöd samt att stödet behöver utvecklas. Följande slutsatser kan dras av studien. Alla individer har olika upplevelser. Det är viktigt att få kunskap om olika copingstrategier, vilket medför att socialt arbete kan hjälpa dem att hantera olika situationer. Samtliga deltagare upplevde att det saknades samarbete och information.

Isothiocyanates (ITCs) are phytochemicals highly expressed in cruciferous vegetables and these compounds are associated with the decreased incidence of cancers in populations consuming high levels of cruciferous vegetables. Several individual ITCs including phenethyl isothiocyanate (PEITC) inhibit tumor growth and angiogenesis and their anticancer activity has been linked to inhibition of cancer cell growth, survival and inflammation (NFB). It has also been demonstrated that PEITC induces reactive oxygen species (ROS) and that ROS is largely responsible for PEITC-induced cell death. To confirm PEITC-induced cancer cell death we have investigated the mechanism of action of PEITC in pancreatic cancer cell lines and PEITC induces ROS and inhibits growth and induces apoptosis (PARP cleavage). In addition, PEITC downregulates expression of several gene products including vascular endothelial growth factor (VEGF), cyclin D1 (CD1), Bcl2 and survivin and these have previously been reported in other studies. However, since these gene products are all regulated by specificity protein (Sp) transcription factors Sp1, Sp3 and Sp4, which are overexpressed in cancer cells and tumors, we investigated the effects of PEITC on Sp proteins and observed that PEITC decreased expression of Sp1, Sp3 and Sp4 in pancreatic cancer cells. These results demonstrate for the first time that an important underlying mechanism of action of ITCs likely involves targeting Sp transcription factors through an ROS-mediated mechanism and the pathways required for ITC-induced Sp downregulation were investigated and the results are presented in this paper.

Progress in DNA sequencing of plant genomes has revealed that, in addition to microorganisms, a number of plants contain genes which share similarity to microbial 1-aminocyclopropane-1-carboxylate (ACC) deaminases. ACC deaminases break down ACC, the immediate precursor of ethylene in plants, into ammonia and α-ketobutyrate. We therefore sought to isolate putative ACC deaminase cDNAs from tomato plants with the objective of establishing whether the product of this gene is a functional ACC deaminase. It was demonstrated that the enzyme encoded by the putative ACC deaminase cDNA does not have the ability to break the cyclopropane ring of ACC, but rather that it utilizes D-cysteine as a substrate, and in fact encodes a D-cysteine desulfhydrase. Kinetic characterization of the enzyme has shown that it is similar to other previously characterized D-cysteine desulfhydrases. Using site-directed mutagenesis, it was shown that altering two amino acid residues within the predicted active site changed the enzyme from D-cysteine desulfhydrase to ACC deaminase. Concomitantly, it was shown that by altering two amino acids residues at the same position within the active site of ACC deaminase from Pseudomonas putida UW4 changed this enzyme into D-cysteine desulfhydrase.

Progress in DNA sequencing of plant genomes has revealed that, in addition to microorganisms, a number of plants contain genes which share similarity to microbial 1-aminocyclopropane-1-carboxylate (ACC) deaminases. ACC deaminases break down ACC, the immediate precursor of ethylene in plants, into ammonia and α-ketobutyrate. We therefore sought to isolate putative ACC deaminase cDNAs from tomato plants with the objective of establishing whether the product of this gene is a functional ACC deaminase. It was demonstrated that the enzyme encoded by the putative ACC deaminase cDNA does not have the ability to break the cyclopropane ring of ACC, but rather that it utilizes D-cysteine as a substrate, and in fact encodes a D-cysteine desulfhydrase. Kinetic characterization of the enzyme has shown that it is similar to other previously characterized D-cysteine desulfhydrases. Using site-directed mutagenesis, it was shown that altering two amino acid residues within the predicted active site changed the enzyme from D-cysteine desulfhydrase to ACC deaminase. Concomitantly, it was shown that by altering two amino acids residues at the same position within the active site of ACC deaminase from Pseudomonas putida UW4 changed this enzyme into D-cysteine desulfhydrase.

Data from longitudinal surveys give rise to many statistical challenges. They often come from a vast, heterogeneous population and from a complex sampling design. Further, they are usually collected retrospectively at intermittent interviews spaced over a long period of time, which gives rise to missing information and loss to follow-up. As a result, duration data from this kind of surveys are subject to dependent censoring, which needs to be taken into account to prevent biased analysis. Methods for point and variance estimation are developed using Inverse Probability of Censoring (IPC) weights. These methods account for the random nature of the IPC weights and can be applied in the analysis of duration data in survey and non-survey settings. The IPC estimation techniques are based on parametric estimating function theory and involve the estimation of dropout models. Survival distributions without covariates are estimated via a weighted Kaplan-Meier method and regression modeling through the Cox Proportional Hazards model and other models is based on weighted estimating functions. The observational frameworks from Statistics Canada's Survey of Labour and Income Dynamics (SLID) and the UK Millenium Cohort Study are used as motivation, and durations of jobless spells from SLID are analyzed as an illustration of the methodology. Issues regarding missing information from longitudinal surveys are also discussed.