The impact of charter schools in Texas

This dissertation examines the effects of charter schools in Texas, using data from the Texas Education Agency for 190 charter schools and over 60,000 charter students. In Chapter II we examine charter effect test score gains for charter students. After controlling for individual student characteristics, we find that students in their first year in a charter school have large negative test score gains compared to when they were in traditional public school, and that charter schools that have been in operation for more than one year have higher average test score gains than new charter schools. Charter schools appear to have the most positive effects on African-American students. We find that the overall effect of being in a charter school for multiple years is that students have slightly lower average test score growth than when they were in a traditional public school. In Chapter III we examine the effect of charters on test score gains for students attending nearby traditional public schools. After controlling for campus and student characteristics, we find traditional public school districts and campuses that face greater competition from charter schools have higher average test score gains than other traditional public schools. This positive effect of charter competition is strongest for African-American and Hispanic students, and is focused entirely on students attending traditional public campuses in the bottom 50% of the initial campus average achievement distribution. In Chapter IV we examine the charter effect on the distribution of students by ability and race/ethnicity, as well as examining what factors are associated with a student choosing to move to a charter school. We find that students who move to charter schools tend to move to schools with a higher percentage of students of their same race/ethnicity, and that this gap is largest for African-American students. We also find that average math and reading test scores are lower than the statewide average at the traditional public schools that charter students leave, and that charter schools are attracting, on average, the lower-performing students from these lowperforming schools

A Rapid Synthetic Approach to the ABCD Core of the <i>Stemona </i>Alkaloids

A new Lewis acid-assisted Brønsted acid cascade approach for the stereoselective formation of the tetracyclic Stemona alkaloid skeleton is described in five steps from epoxide 15. Crucially, this tetracyclic product can be accessed as either C13 epimer, potentially serving as intermediates for the synthesis of a range of Stemona alkaloids

Unusually Facile Thermal Homodienyl-[1,5]-Hydrogen Shift Reactions in Photochemically-Generated Vinyl Aziridines

A range of photochemically generated tri‐ and tetracyclic vinyl aziridines have been found to undergo a general and surprisingly low temperature ring opening through a [1,5]‐hydrogen shift reaction. The rate of the process was found to be highly dependent on the structure and substitution around the azirdine ring and the alkene terminus, with some substrates being observed to undergo ring opening at temperatures as low as 25 °C. The rigid nature of these polycyclic systems precludes a conformational explanation of these rate differences, and an Eyring study confirmed a negligible entropic barrier to the reaction. However, the Eyring plots for two different aziridines systems showed a significant difference in their enthalpies of activation. It is therefore believed that the levels of aziridine ring strain, as well as electronic effects, are the dominant factors in this sequence

How efficiently can HEPA purifiers remove priority fine and ultrafine particles from indoor air?

More than 1 million premature deaths in Asia annually are estimated to be associated with indoor air quality. HEPA (high-efficiency particulate air) filter air purifiers (APs) are widely used in urban Chinese residences by the growing middle class, as public awareness of air pollution increases. Currently, understanding of how particle size affects particle removal is inconsistent, and the rate at which different particle types are removed remains largely unknown. Therefore, this investigation aimed to determine the relationship between particle size and the removal efficiency of particles, and how efficiently ambient air is filtered compared to standard particle types which are typically used for such tests (tobacco smoke, dust and pollen). Three of the most popular AP models in China were tested in China’s largest indoor controlled chamber laboratory and the removal efficiencies of particles in the 18-514nm range were identified. Each AP had a distinct profile of removal efficiency against particle size, but the three APs shared similarities in performance, with removal efficiency consistently lowest at 200-250nm. This size fraction is important in an exposure context as these particles are abundant in ambient air in mega-cities, can penetrate through building shells effectively, remain airborne for long periods of time and can penetrate the deepest areas of the lungs. Ambient air particles were removed at a similar rate to test particles; this confirms that the Association of Home Appliance Manufacturers’ (AHAM) standards are a suitable proxy for “real world” performance

Short Flow-Photochemistry Enabled Synthesis of the Cytotoxic Lactone (+)-Goniofufurone

A photochemical approach to the cytotoxic lactone (+)-goniofufurone (1) is reported. Paterno−̀ Büchi [2 + 2] photo- cycloaddition from known enol ether 4, derived from the readily available sugar D-isosorbide, yielded oxetane 7. This slow, dilute reaction was scaled up by using flow photochemistry to yield &gt;40 g of 7. Installation of the key lactone ring was achieved via a unique Wacker- style oxidation of an enol−ether bond. Acid-catalyzed aqueous ring opening provided 1 in five steps from 4 (11.5% overall)

Pd(II)-Catalyzed [4 + 2] Heterocyclization Sequence for Polyheterocycle Generation

A new Pd­(II)-catalyzed cascade sequence for the formation of polyheterocycles, from simple starting materials, is reported. The sequence is applicable to both indole and pyrrole substrates, and a range of substituents are tolerated. The reaction is thought to proceed by a Pd­(II)-catalyzed C–H activated Heck reaction followed by a second Pd­(II)-catalyzed aza-Wacker reaction with two Cu­(II)-mediated Pd(0) turnovers per sequence. The sequence can be considered a formal [4 + 2] heterocyclization