Various needle trap devices (NTDs) with different designs for different applications have been developed during the past decade. A theoretical model on the fundamentals of the NTD was recently proposed, which employed the theory of frontal (gas-solid) chromatography to describe the sampling process, where a gaseous sample was continuously introduced into the sorbent bed. In this investigation, different types of sorbent particles with different dimensions were packed into the needle as adsorbents. The effect of particle dimension, which would affect the packing density and consequently the capacity, the extraction efficiency, and desorption efficiency of the NTD were experimentally investigated and the proposed theory was validated. The results demonstrated that NTDs packed with small particles possess higher extraction capacity and efficiency but much higher resistance to flow as well. The higher resistance did not necessarily result in poor desorption efficiency, because desorption efficiency was affected by both the sorbent bed structure and the desorption gas flow. The relationships observed among those physical parameters provide valuable guidance on how to design an NTD with high performance potential for future applications. For particulate sampling, it was found that NTDs packed with different particles presented high collection efficiency of the particulates being investigated, and the collection efficiency was dominated by the pore size and distribution of the sorbent bed packed inside the needle. Collection efficiency also increased with increase in solidity of the sorbent bed; the increase in humidity of the aerosol sample; and the decrease of sampling rate. The results also provide valuable guidance on the optimisation of needle trap for particulate collection.

Schizophrenia may result from altered gene expression leading to abnormal neurodevelopment. In a search for genes with altered expression in schizophrenia, cDNA library subtractive hybridization experiments using post-mortem human frontal cerebral cortices from schizophrenia individuals and neurological controls were performed. I found the mRNA of two neurodevelopmentally important genes, Nogo (RTN4) and calcium/calmodulin-dependent protein kinase II beta (CaMKIIβ), to be overexpressed in post-mortem frontal cortex tissues from patients who suffered with schizophrenia. I used the quantitative real-time polymerase chain reaction method to determined the mRNA levels of these genes in tissues from age- and sex-matched individuals. Nogo is a myelin-associated protein which inhibits the outgrowth of neurites and nerve terminals. The gene produces three splice variants, Nogo-A, B and C. I found Nogo-C mRNA to be overexpressed by 26% in schizophrenia. I also found a 17% reduction of Nogo-B mRNA in samples from individuals who had been diagnosed with severe depression. Furthermore, I showed that there is a direct correlation between the expression of both Nogo-A and -C and the presence of a CAA insert in the 3’UTR of the Nogo gene. CaMKII is a kinase localized at the postsynaptic density. The holoenzyme is primarily composed of the subunits α and β, encoded by two separate genes. It influences the expression of many neuroreceptors, in particular receptors of the glutamatergic pathway. CaMKII also mediates neural maturation during puberty, a time of onset of schizophrenia. The expression of CaMKIIα was elevated 29% in frontal cortex tissues of patients who suffered from depression. The expression of CaMKIIβ was elevated 27% in tissues of schizophrenia patients and 36% in tissues of patients diagnosed with depression. Upregulation of CaMKIIβ was associated with the presence of the CAA insert in at least one copy of the Nogo gene in a group containing both healthy subjects and patients with mental illness, possibly linking the CaMKII and Nogo pathways. The values for the expression of Nogo, CaMKIIα and CaMKIIβ were normalized to β-glucuronidase expression to minimize the effects of mRNA degradation. These results confirm that upregulation of Nogo-C and CaMKIIβ is likely associated with schizophrenia.

Working memory (WM) capacity – the capacity to maintain and manipulate information in mind – plays an essential role in high-level cognitive functions. An important determinant of WM capacity is the ability to resolve interference of previously encoded but no longer relevant information (proactive interference: PI). Four different mechanisms of PI resolution involving binding and inhibition have been proposed in the literature, although debate continues regarding their role. Braver et al. (2007) introduced an important distinction in the PI resolution literature, proposing two general types of PI control mechanisms that occur at different time points: proactive control (involves preparation in advance of the interference) and reactive control (occurs after interference occurs). This thesis proposed that among these four functions involving binding and inhibition, item inhibition and binding could be involved in proactive control, while familiarity inhibition and episodic inhibition could be involved in reactive control. The question is which mechanism in each pair is indeed involved in proactive control and reactive control respectively, and how these proactive control and reactive control mechanisms work together to resolve PI. In addition, do these mechanisms play a role in the relationship between PI resolution and WM? In an individual differences study, individuals’ ability to resolve PI was assessed in memory tasks, with two versions of each that encouraged the use of either proactive or reactive control. In addition, measures were obtained of individuals’ ability of binding and inhibition in tasks that had minimal memory demands. Regression analyses showed contributions of binding and inhibition to PI resolution and WM. Moreover, these functions are responsible for the correlation between PI resolution and WM. In a neuroimaging study, the neural basis of proactive control was examined by comparing two memory tasks that differed in their demand on binding and inhibition. In addition, the brain regions engaged in reactive control was examined by contrasting trials involving interference or not. The thesis showed that item inhibition carried out by the left inferior frontal cortex (IFC) is involved in proactive control while episodic inhibition carried out by the left IFC and the posterior parietal cortex is involved in reactive control.

Aging is typically associated with declining mental abilities, most prominent for some forms of memory. There are, however, large inter-individual differences within the older population. Some people experience rapid decline whereas others seem almost spared from any adverse effects of aging. This thesis examined the neural underpinnings of such individual differences by using longitudinal observations of episodic memory change across 15-20 years, combined with structural and functional magnetic resonance imaging of the brain. Study I found significant correlations between volume and activity of the hippocampus (HC), and memory change over a 6-year period. That is, individuals with decline in HC function also had declining memory. In contrast, Study II showed that successfully aged individuals, who maintained high memory scores over 15-20 years, had preserved HC function compared to age-matched elderly with average memory change. The successful agers had HC activity levels comparable to those of young individuals, as well as higher frontal activity. Study III revealed that individual differences in memory ability and brain activity of elderly reflect both differential age-related changes, and individual differences in memory ability that are present already in midlife, when age effects are minimal. Specifically, memory scores obtained 15-20 years earlier reliably predicted brain activity in memory-relevant regions such as the frontal cortex and HC. This observation challenges results from previous cross-sectional aging studies that did not consider individual differences in cognitive ability from youth. Collectively the three studies implicate HC and frontal cortex function behind heterogeneity in cognitive aging, both substantiating and qualifying previous results from cross-sectional studies. More generally, the findings highlight the importance of longitudinal estimates of cognitive change for fully understanding the mechanisms of neurocognitive aging. / <p>At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 3: Manuscript.</p>

<p>Feedback control of Chest Acceleration or Chest Deflection is believed to be a good way of minimizing the risk of injury. In order to implement such a controller in a car, an observer estimating these responses is needed. The objective of the study was to develop a model of the dummy’s chest capable of estimating the Chest Acceleration and the Chest Deflection during frontal crashes in real time. The used sensor data come from car accelerometer and spindle rotation sensor of the belt, the data has been collected from dummies during crash tests. This study has accomplished the aims using a simple linear model of the chest using masses, springs and dampers. The parameters of the model have been estimated through system identification. Two types of black-box models have also been studied, one ARX model and one state-space model. The models have been tested and validated against data coming from different crash setups. The results show that all of the studied models can be used to estimate the dummy responses, the physical grey-box model and the black-box state-space model in particular.</p> / <p>Genom att använda återkoppling av storheterna bröstacceleration och bröstintryck antas man kunna minska risken för skador vid krockar i personbilar. För att kunna implementera detta behövs en observatör för dessa storheter. Målet med denna studie är att ta fram en modell för att kunna skatta accelerationen i bröstkorgen samt bröstintrycket i realtid i frontala krockar. Sensordata som använts kom från en accelerometer och en givare för att mäta rotationen i bältessnurran. Detta har gjorts genom att modellera bröstkorgen med linjära fjädrar och dämpare. Dess parametrar har skattats från data från krocktester från krockdockor. Två s.k. black-box-modeller har också tagits fram, en ARX-modell och en på tillståndsform. Modellerna har testats och validerats mha data från olika sorters krocktester. Resultaten visar att alla studerade modeller kan användas för att skatta de ovan nämnda storheterna, den fysikaliska modellen och black-box-modellen på tillståndsform fungerade bäst.</p>

Ce mémoire présente une revue bibliographique et des données sur les bases comportementales et neurophysiologiques de l'apprentissage de comportement séquentiels chez le primate

Physical processes in the Gulf of Mexico (GOM) and mesoscale (10-300 km) processes associated with the Loop Current are fairly well known. However, little is known about the physical/ biological interactions of the frontal boundary system of the Loop Current. Zooplankton abundance and distribution was determined at 28 stations in the vicinity of the Loop Current. Species richness was high at all stations. Copepods comprised 60% of the total zooplankton collected. Oithona plumifera, Nannocalanus minor and Euchaeta marina were the most abundant copepods. Chaetognaths and ostracods were also very abundant and made up 11 and 5 % respectively of the zooplankton total. Total zooplankton abundance was higher at the boundary of the LC than it was inside the LC but not significantly different from abundances outside of the LC. Stations in the western Gulf of Mexico and on the western boundary had the highest abundances of zooplankton overall. The chlorophyll concentrations at the chlorophyll maximum were higher at the boundary of the LC than inside the LC. Physical-biological processes associated with the frontal boundary of the LC appear to influence the abundance and distribution of zooplankton in the GOM.

When making decisions, individuals evaluate several possible outcomes of their choice; however, some display heightened reward sensitivity, despite the potential for future negative consequences, which can lead one to make risky choices. Rewards are processed in the mesolimbic dopamine reward system, and this system is in part modulated by genetic polymorphisms that are associated with dopamine transmission. The current study tested if genetic polymorphisms that are associated with enhanced dopamine neurotransmission will be more neurally reward sensitive, score higher on self-reported impulsivity, and make riskier choices. In a sample of 85 participants, five genetic polymorphisms were genotyped and used to create a genetic risk score that represented dopamine transmission efficiency. Two groups (high and low efficiency) were created via median split and then compared on neural reward sensitivity (assessed by event-related potentials, specifically, the medial-frontal negativity [MFN] and the error-related negativity), impulsivity (assessed via self-report), and risky choice (measured using the Balloon Analogue Risk Task and self-report measures). Results indicated that individuals with higher levels of dopamine displayed a less negative MFN and more drinking behaviors than those with lower levels of dopamine. These results suggest that individuals with higher levels of dopamine are less sensitive to punishments, which could lead them to make riskier choices.

Premenstrual dysphoric disorder (PMDD) is a severe dysphoric form of premenstrual syndrome (PMS) that is included as a diagnosis for further study in the DSM-IV (APA, 2000). A primary aim of the present study was to characterize the co-occurrence of PMDD and major depression, in a sample that spans the entire range of depressive severity. The range included non-depressed controls, women meeting criteria for dysthymia, and women meeting criteria for current Major Depressive Disorder (MDD). Co-occurrence of MDD and PMDD were only statistically significant when considering Lifetime MDD. Resting frontal electroencephalographic (EEG) asymmetry has been hypothesized to tap a diathesis toward depression or other emotion-related psychopathology. Another primary aim was to assess Frontal EEG asymmetry in college women who meet criteria for Pre-Menstrual Dysphoric Disorder (n = 25) and 25 matched controls. Participants were assessed four times in a two week period. Women reporting low premenstrual dysphoric symptomatology exhibited greater relative left frontal activity at rest than did women high in premenstrual dysphoric symptomatology. These results are consistent with a diathesis-stress model for premenstrual dysphoric symptomatology. A secondary aim was to assess whether individuals with PMDD or menstrual related mood variability, but no current diagnosis of depression, have an increased family history of depression. Promising evidence of a relationship between family history of MDD and a likelihood of PMDD was discovered. A trend was found for Spectrum PMDD women: a higher rate of Family History of MDD (36%) than non PMDD women (19.6%). Ideally, resting frontal electroencephalographic (EEG) asymmetry could help us learn more about the etiology of depression and hormonal-related depression specifically, and test whether they may share etiological factors.

Feedback control of Chest Acceleration or Chest Deflection is believed to be a good way of minimizing the risk of injury. In order to implement such a controller in a car, an observer estimating these responses is needed. The objective of the study was to develop a model of the dummy’s chest capable of estimating the Chest Acceleration and the Chest Deflection during frontal crashes in real time. The used sensor data come from car accelerometer and spindle rotation sensor of the belt, the data has been collected from dummies during crash tests. This study has accomplished the aims using a simple linear model of the chest using masses, springs and dampers. The parameters of the model have been estimated through system identification. Two types of black-box models have also been studied, one ARX model and one state-space model. The models have been tested and validated against data coming from different crash setups. The results show that all of the studied models can be used to estimate the dummy responses, the physical grey-box model and the black-box state-space model in particular. / Genom att använda återkoppling av storheterna bröstacceleration och bröstintryck antas man kunna minska risken för skador vid krockar i personbilar. För att kunna implementera detta behövs en observatör för dessa storheter. Målet med denna studie är att ta fram en modell för att kunna skatta accelerationen i bröstkorgen samt bröstintrycket i realtid i frontala krockar. Sensordata som använts kom från en accelerometer och en givare för att mäta rotationen i bältessnurran. Detta har gjorts genom att modellera bröstkorgen med linjära fjädrar och dämpare. Dess parametrar har skattats från data från krocktester från krockdockor. Två s.k. black-box-modeller har också tagits fram, en ARX-modell och en på tillståndsform. Modellerna har testats och validerats mha data från olika sorters krocktester. Resultaten visar att alla studerade modeller kan användas för att skatta de ovan nämnda storheterna, den fysikaliska modellen och black-box-modellen på tillståndsform fungerade bäst.