3-Oxabicyclo[3,2,0]hepta-1,4-diene

3-Oxabicyclo[3,2,0]hepta-1,4-diene (3) has been synthesized by partial hydrogenation of 3-oxabicyclo-[3,2,0]hepta-1,4,6-triene (2)

Doctor of Philosphy

dissertationIntracellular cargos are shuttled around the cell via molecular motor proteins along their respective filament substrates. For decades, biophysicists have taken advantage of in vitro techniques to study fine details of the molecular motor machinery. Today, thanks in large part to in vitro experimentation, a great deal is known about the structure-function relationship of various motors, including kinesin-1. The field is now shifting to investigate how multiple motors work together to transport cargos around the cell's complex microtubule (MT) network. Due to the complexity of the cell's complex biochemical makeup and the heterogeneity of its three-dimensional (3D) MT network, this topic is virtually impossible to address quantitatively in the native cellular environment. Instead, in vitro experiments must be used to ensure full control over all relevant variables to study how geometry alone, impacts cargo transport. Traditional in vitro bead assays cannot faithfully model the cell's 3D MT network, and thus cannot be used to test how MT network geometry (orthogonal filament separation, or crossing angle) affects cargo transport. To remedy this, we developed a novel in vitro method to manipulate individual MT filaments in 3D with nanometer precision. With this technique, we constructed MT-MT crossings with various geometries to test how separation distance and angle between MT filaments impact transport behaviors of artificial model cargos driven by kinesin-1. We find that variable separation distance and angle influence cargo navigational behaviors at MT-MT crossings. We also use our experimental data to constrain a 3D simulation to probe aspects of the overall transport system that are not possible to assay experimentally. We propose detailed mechanisms that underlie the MT network's influence on cargo transport

Heart rate adjustment of the time-voltage ST segment integral: Identification of coronary disease and relation to standard and heart rate-adjusted ST segment depression criteria

AbstractTo assess the effect of heart rate adjustment of the magnitude of the ST integral (ST-HR integral) on exercise test performance, the exercise electrocardiogram (ECG) of 50 clinically normal subjects and 100 patients with known or suspected coronary artery disease was analyzed. At matched specificity of 96% with standard ECG criteria (≥0.1 mV of additional horizontal or downsloping ST segment depression), ar unadjusted ST integral partition of 16 μV-s identified coronary disease in the 100 patients with known or suspected disease with a sensitivity of only 41%, a value significantly lower than the 59% sensitivity of standard ECG criteria (p < 0.01) and the 65% sensitivity of an ST depression partition of 130 μV (p < 0.001).However, test performance of the ST integral was greatly improved by simple heart rate adjustment: at a matched specificity of 96%, an ST-HR integral partition of 0.154 μV-s/beat per min identified coronary disease in the 100 patients with a sensitivity of 90%, a value significantly greater than the 59% sensitivity of standard criteria and 65% sensitivity of ST depression criteria (each p < 0.001) and similar to the 91% sensitivity of the ST-HR index and 93% sensitivity of the ST-HR slope (each p = NS). Comparison of receiver-operating characteristic curves confirmed the superior overall test performance of the ST-HR integral relative to the ST integral and ST segment depression, and demonstrated improved performance that was comparable with that of the ST-HR index and the ST-HR slope.These findings support the value of heart rate adjustment of end-exercise repolarization changes during exercise electrocardiography and demonstrate that this approach significantly improves the performance of the ST integral in identifying coronary artery disease

Study of temperature, air dew point temperature and reactant flow effects on PEMFC performances using electrochemical spectroscopy and voltammetry techniques

A single PEMFC has been operated by varying the assembly temperature, the air dew point temperature and the anode/cathode stoichiometry rates with the aim to identify the parameters and combinations of factors affecting the cell performance. Some of the experiments were conducted with low humidified reactants (relative humidity of 12%). The FC characterizations tests have been conducted using in-situ electrochemical methods based on load current and cell voltage signal analysis, namely: polarization curves, EIS measurements, cyclic and linear sweep voltammetries (CV and LSV). The impacts of the parameters on the global FC performances were observed using the polarization curves whereas EIS, CV and LSV test results were used to discriminate the different voltage loss sources. The test results suggest that some parameter sets allow maximal output voltages but can also induce material degradation. For instance, higher FC temperature and air flow values can induce significant electrical efficiency benefits, notably by increasing the reversible potential and the reaction kinetics. However, raising the cell temperature can also gradually dry the FC and increase the risk of membrane failure. LSV has also shown that elevated FC temperature and relative humidity can also accelerate the electrolyte degradation (i.e. slightly higher fuel crossover rate) and reduce the lifetime consequently. PEMFC; Characterization; Electrochemical Impedance Spectroscopy; Cyclic Voltammetry; Linear Sweep Voltammetr

Developing working conditions

The overall aim of this thesis was to investigate working conditions and organizational strategies providing conditions for job resources with potential for development, positive well-being and health. The aim was formed on the assumption that the organization affects working conditions, working conditions affects employees‟ development, well-being, health and sickness absence. Both a qualitative case study design and a longitudinal epidemiologic design were used in this thesis. These two different approaches are complementary in enhancing scientific knowledge as well as providing implementable tools for development and reduced absenteeism. Study I was a qualitative study aiming at identifying manageable organizational factors affecting working conditions and sickness absence. Interviews primarily with managers were analyzed with a qualitative thematic approach. This was made to distinguish organizational features characterizing companies with low compared to average levels of sickness absence. The results revealed strategies and procedures in leadership, employee development, communication, employee participation and involvement, corporate values and visions and strategies for employee health, as characterizing companies with low levels of sickness absence. In study II the organizational conditions and strategies for creating job resources in companies with low levels of sickness absence was explored and described by using the same qualitative method as in study I. Organizational conditions for following job resources were found: Authority, Autonomy, Support, Skill utilization, Feedback, Role clarity, Predictability, and Learning possibilities. A main finding was that strategies and conditions for job resources were found to be provided for both leaders and employees through the active use of teams. Another main finding was that the companies were providing different kinds of learning opportunities, regulated by personal development plans. The third study, a study of the active learning hypothesis conducted with a longitudinal and population based design, scrutinizes demands and control as antecedents for learning according to the Job Demand Control model. Logistic regression analyses were used to estimate the associations. Results showed positive main effects of skill discretion, task authority, and control, as well as a positive effect of active and low strain working conditions on developing problem-solving skills, indicating that working conditions including high levels of control may positively affect coping skills and behavior also in the non-work domain. However, levels of non-participation were high in this study. Therefore, an extensive analysis of non-participation was made in study IV. Multivariate logistic regressions revealed that the rates of non-response were higher among males, younger persons, singles, those with lower income, lower education and those born outside the Nordic countries. This led to an overrepresenta-tion of Nordic, older, married women with high education and income, in the sample used in study III. The overall conclusion of this thesis is that working conditions and organizational strategies to provide job resources have effect on levels of sickness absence and development

Spitzer measurements of atomic and molecular abundances in the Type IIP SN 2005af

We present results based on Spitzer Space Telescope mid-infrared (3.6-30 micron) observations of the nearby IIP supernova 2005af. We report the first ever detection of the SiO molecule in a Type IIP supernova. Together with the detection of the CO fundamental, this is an exciting finding as it may signal the onset of dust condensation in the ejecta. From a wealth of fine-structure lines we provide abundance estimates for stable Ni, Ar, and Ne which, via spectral synthesis, may be used to constrain nucleosynthesis models.Comment: ApJ Letters (accepted