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

The Effects of School Integration: Evidence from a Randomized Desegregation Program

This paper studies the impact of a desegregation ruling on several medium-run outcomes. This ruling mandates that seven school districts, which serve higher-income, predominantly-white families, accept a group of minority elementary school students who apply to transfer from a nearby, predominantly-minority school district. Slots are allocated via lottery. The offer to transfer raises college enrollment by 10 percentage points. This is due to greater attendance at two-year colleges and particularly for male students. There is evidence male students are also more likely to vote. In contrast, transferring increases the likelihood of arrest. This is driven by increases in non-violent offenses

Leveraging Technology to Engage Parents at Scale: Evidence from a Randomized Controlled Trial

While leveraging parents has the potential to increase student performance, programs that do so are often costly to implement or they target younger children. We partner text-messaging technology with school information systems to automate the gathering and provision of information to parents at scale. In a field experiment across 22 middle and high schools, we used this technology to send automated text-message alerts to parents about their child’s missed assignments, grades and class absences. We pre-specified five primary outcomes. The intervention reduces course failures by 38% and increases class attendance by 17%. Students are more likely to be retained in the district. The positive effects are particularly large for students with below-average GPA and students in high school. There are no effects on standardized test scores however. We randomly chose either the mother or the father to receive the alerts, but there were no differential effects across these subgroups. As in previous research, the intervention appears to change parents’ beliefs about their child’s performance and increases parent monitoring. Our results show that this type of automated technology can improve student effort relatively cheaply and at scale

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

The Effects of Making Performance Information Public: Evidence from Los Angeles Teachers and a Regression Discontinuity Design

In theory, the publication of performance ratings may improve performance through reputation concerns and peer effects or impede performance by demoralizing employees. This paper uses school-district data and a regression discontinuity design to answer how consumers and employees respond to making performance information public. We find that high-performing students sorted into classrooms with highly-rated teachers as a result of publication. Teachers who were published do not perform better or worse than teachers who were not published on average. This average effect is due to the heterogeneous impact of publication; highly-rated teachers perform worse following publication while low-rated teachers perform better. On net, the gap between high and low-performing students closes slightly as a result

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