Income variability explains a significant fraction of the increase in annual income inequality. Chapter 1 considers the impact of variability on tax unit inequality. Using income tax return panel data, I estimate that between a tenth and a quarter of the increase in top one percent income shares between the early 1980s and 2000s was caused by variability. Increased income variability over this period resulted from mean-reverting fluctuations in the bottom quintile and top one percent. Variability in the top of the distribution seems partly driven by permanent income shifting in response to the Tax Reform Act of 1986. Chapter 2 examines the individual earnings distribution. Using Social Security Administration earnings panel data, I estimate that variability explains half of the increase in annual inequality in the bottom half of the distribution between 1973 and 1985. When workers with years of zero earnings are included, increasing earnings variability explains almost all of this group's increase in inequality. The increase in earnings variability appears to be explained by an increased fraction of working age men with years of zero earnings. Annual individual earnings inequality in the bottom half of the distribution not only increased with variability in the 1970s and 1980s, but also fell with variability in the 1950s and early 1960s. This suggests that the U-shaped trend in income inequality observed over these four decades was partly caused by first a fall and then a rise in earnings variability. Between 1985 and 2000, falling variability caused most of the decline in annual earnings inequality within the bottom half of the distribution. Within the top of the distribution, earnings inequality increased over this period because of changes in permanent earnings and not increasing variability. Income variability means that in a progressive tax system annual and lifetime federal tax rates can diverge. Chapter 3 shows that on an annual basis, those at the bottom of the distribution pay little or no federal income taxes, while on a lifetime basis they pay average tax rates about five percentage points higher. Income variability also means there is a trade-off between vertical and horizontal equity.

This thesis takes the typical one-to-one relationship between a tower and a lobby and asks what if a three-layer base that produces a higher density and a scale exceeding the physical boundary of a single office tower replaces the lobby. Combing retail, conference facilities and recreation the base at once consolidates the programmatic needs of office workers and thickens the singular exchange of lobby-office-lobby to one of recreation-lobby-retail-office-lobby. Spanning the length of a ten-acre site in London, the base establishes a large horizontal floor plate and introduces big-box retail and an economy privileging lower prices onto a site surrounded by boutiques and mom-and-pop stores. Instead of planar adjacencies, retail and towers overlay in section. Vertical, horizontal and transverse circulations intersect, turn and unite, forming new programmatic possibilities and proliferating the cultural, economic and social life of a tower onto the city.

This inquiry explores the possibility of applying principles from Plato?s education system in the Republic to modern military leadership development programs. Both are concerned with producing a ?guard-dog? that will serve the interests of the state rather than exploit vulnerable civilians. Plato proposes educating guardians with a natural disposition to believe the ?noble lie,? that it is better to serve others than to pursue selfinterest for personal gain; but, would the proper tension in moral sensibilities prescribed by the Platonic Grid help or hinder a military leader to successfully act on the battlefield? First, I examine Plato?s theory to familiarize military leaders with the education system from the Republic; including his views on unity, reality, the theory of the forms, and recollection of knowledge that underlie Plato?s enquiry into the nature of justice, and lead to the need for inner harmony of the soul through the proper tension of wisdom, courage, and temperance to rule the three elements of the soul. Then I analyze the key leaders from the Battle of Balaclava, the Battle of Gettysburg, and the siege of the Alamo for possible correlations of the application of the Platonic Grid aligned with the ?noble lie? to success on the battlefield. This includes inquiry into the likelihood that belief in the ?noble lie? can motivate soldiers to make the ultimate sacrifice. I conclude by examining how Plato?s theories could be assimilated into a military pedagogy to produce modern day ?dogs of war? that leads to the startling conclusion that adherence to the ?noble lie? could also be in the self-interest of the guardian who seeks to serve the best interest of her nation.

Lipid bi-layers are ubiquitous components of biological cells and are found in a variety of cell components. In biological membranes, lipid bi-layer membranes carry membrane proteins, which control transport of material and communication of signals in and out the cell. There are several disadvantages involved with patch clamping method as a way of studying biological membranes and protein interactions. Hence, artificial synthesis of bi-layer has been of great interest in basic biophysical studies, drug discoveries in pharmaceutical studies and study of protein nanopores for precise engineering applications. However, conventional lipid bi-layer synthesis techniques require skilled operators, have low repeatability (reliability), have portability restrictions and result in unstable bi-layers having a short lifetime. In this investigation a novel microfluidic device and a method for artificial synthesis of lipid bi-layer in-situ are explored. In the proposed method, lipid trapped at an aperture on a Teflon sheet, is thinned to form a lipid bi-layer by a continuous flow of buffer solution on both sides of the aperture in the microfluidic device. The microfluidic device is expected to have advantages from its compact design. Further, the new approach is expected to be repetitive and good for automation removing the requirement of a skilled operator. The microfluidic device was fabricated using two glass substrates. Two channels of ? ? shape were etched and through holes were fabricated at all four terminal ends of the microchannels on each glass substrate. A thin Teflon sheet carrying a 100?m diameter hole was sandwiched between the two glass wafers forming two sets of microchannels on both sides of the aperture. An analytical microfluid model of the microchannels was developed to investigate the nature of the flow and to select microchannel parameters. Experiments using the proposed device were performed to verify the feasibility of the novel approach for lipid bi-layer synthesis. Experimental results suggest formation of a lipid bi-layer at an aperture on the Teflon sheet but further investigation might be necessary for verification. Life time of the bi-layer is short mainly due to low quality of the used aperture.

This study constructs a two-step model to test the most prominent market timing factors. We decompose equity issuances into 1) firm-specific components, which are predicted by firms’ characteristics, and 2) market-wide components, which are predicted by aggregate time series measures. Our evidence shows that, at the firm level, firms with higher market-to-book ratio, smaller size, more growth opportunities, and fewer tangible assets are more likely to issue equity. At the aggregate level, a greater proportion of firms issue equity in years with higher aggregate market-to-book ratio and lower asymmetric information. After controlling for the aggregate market-to-book ratio and information asymmetry, sentiment has no direct effect on equity issuance. This paper provides direct evidence that firms time their favorable market conditions to reduce adverse selection costs, and to exploit higher individual security valuations or capture growth opportunities.

The middle Cambrian (Drumian) Rockslide Formation is a deeper-water succession of mixed carbonates and siliciclastics. At the Ravens Throat River location it hosts a Burgess Shale-type (BST) deposit. The BST units are found in two separate 1m thick horizons of green-coloured calcareous mudstone and contain a biota similar to that of the Wheeler and Marjum formations of Utah, and to some extent the Burgess Shale itself. The biota is low in diversity and preserves mainly robust soft-tissue parts. The lithologically heterogeneous composition of the formation (shale, dolomite, lime mudstone, sandstone, mudstone) and absence of metamorphism offer an opportunity to analyze the depositional environment and taphonomy of this deeper water unit. Geochemical analysis including, trace elements, organic carbon, biomarker, and synchrotron were attempted and yielded varying results. Trace element ratios, particularly V/Sc, indicate low oxygenation of the bottom waters during the deposition of the fossil-bearing interval. These results differ from most other BST deposits, which suggest that oxygenated bottom waters were maintained throughout sedimentation. In addition, organic matter in the sediments and δ13Corg values suggest the presence of benthic microbial mats. Silver is concentrated mostly in nm to μm-sized particles in the fossilifereous calcareous mudstone, suggesting elevated levels in the depositional environment. Organic films and the evidence for hyoliths feeding on them suggest an in situ preservation of the biota, perhaps from sudden and short anoxic events and quick burial under either microbial mats or the muddy sediment. This is also supported by the presence of only very rare trace fossils.

Recent anecdotal evidence has suggested that Lake Diefenbaker, a large reservoir in southern Saskatchewan, Canada, has been experiencing an increased frequency and severity of algal blooms, suggesting significant alterations in water quality. Due to limited historical water quality monitoring, a paleolimnological investigation of Lake Diefenbaker sediments was conducted in order to interpret spatial and temporal trends in the physicochemistry of sediment cores collected from mid-channel locations along a spatial gradient. Total phosphorus and three sediment species of phosphorus (apatite inorganic phosphorus, non-apatite inorganic phosphorus (NAIP) and organic phosphorus (OP) were measured along the vertical profile of the cores to interpret nutrient loading trends. Trends in historical primary productivity were inferred based on total organic carbon, total nitrogen, δ15N values and the organic carbon to nitrogen (C:N) ratios. In addition, sub-fossil biological remains of diatoms and chironomid larvae were isolated from selected subsections of the sediment cores and identified to assess shifts in community compositions and to infer historical changes in reservoir water quality conditions. Up-reservoir sampling locations showed consistent concentrations of total phosphorus and the three species of phosphorus, organic carbon, nitrogen, δ15N values and C:N ratios in the vertical profile of collected sediment cores. This suggested relatively consistent nutrient loading and primary production in the up-reservoir regions for the period represented by the core profiles. Down-reservoir sediment cores showed an increasing trend in total phosphorus concentration, mainly in the more biologically available NAIP and OP fractions, and enrichment in organic carbon, nitrogen and 15N in more recently deposited sediments. This combined with a decreasing C:N ratio in more recent sediments suggests increased nutrient loading to the sediments and increasing primary productivity at down-reservoir sites. Strong correlations between sediment total organic carbon content and the more biologically available sediment phosphorus fractions (NAIP and OP) suggest that phosphorus deposition patterns are strongly influenced by primary productivity within the reservoir. The compositions of diatom and chironomid communities were consistent over time at up-reservoir locations, with Stephanodiscus parvus dominating the diatom communities and Procladius sp. dominating the chironomid communities. This suggests relatively stable and consistent trophic status and primary productivity in this region. Conversely, major shifts occurred in the diatom and benthic chironomid communities at down-reservoir locations. These shifts were consistent with typical reservoir ontogeny. A shift in dominance from Stephanodiscus parvus to Asterionella formosa, Tabellaria flocculosa and Stephanodiscus medius followed by a shift to Aulacosiera ambigua suggests an initial period of eutrophy, followed by a period of mesotrophy, and finally a transition into a more productive system in recent years. The increase in relative abundance of the chironomid tribe Tanytarsini suggests rising levels of organic matter sedimentation, likely due to increased autochthonous primary productivity. Low chironomid head capsule counts were observed at all locations within Lake Diefenbaker. Despite the low head capsule counts, a 10-day whole-sediment toxicity test using Chironomus dilutus, revealed that Lake Diefenbaker sediments, in proximity to two potential point sources of contamination (aquaculture and municipal discharge), as well as two reference locations, were not of toxicological concern. Despite the lack of toxicity associated with Lake Diefenbaker sediments, it was concluded that Lake Diefenbaker sediments are likely poor habitat for chironomids. This study suggests that primary productivity and nutrient status has remained relatively constant at up-reservoir locations for the period represented by the collected cores. This is likely due to up-reservoir locations being more riverine than down-reservoir regions, which results in increased turbidity causing phytoplankton populations to be light limited. Primary productivity appears to increase spatially with increased distance down reservoir, likely due to a gradual transition to more lacustrine environments, resulting in less turbidity and less light limitation. Temporally, down-reservoir locations appear to be showing increases in primary productivity and nutrient entrainment in sediments. This is likely a result of increased nutrient availability over time and entrainment of these nutrients in sediments at down-reservoir locations by primary producers.

Technology scaling of CMOS devices has made the integrated circuits vulnerable to single event radiation effects. Scaling of CMOS Static RAM (SRAM) has led to denser packing architectures by reducing the size and spacing of diffusion nodes. However, this trend has led to the increase in charge collection and sharing effects between devices during an ion strike, making the circuit even more vulnerable to a specific single event effect called the single event multiple-node upset (SEMU). In nanometer technologies, SEMU can easily disrupt the data stored in the memory and can be more hazardous than a single event single-node upset. During the last decade, most of the research efforts were mainly focused on improving the single event single-node upset tolerance of SRAM cells by using novel circuit techniques, but recent studies relating to angular radiation sensitivity has revealed the importance of SEMU and Multi Bit Upset (MBU) tolerance for SRAM cells. The research focuses on improving SEMU tolerance of CMOS SRAM cells by using novel circuit and layout level techniques. A novel SRAM cell circuit & layout technique is proposed to improve the SEMU tolerance of 6T SRAM cells with decreasing feature size, making it an ideal candidate for future technologies. The layout is based on strategically positioning diffusion nodes in such a way as to provide charge cancellation among nodes during SEMU radiation strikes, instead of charge build-up. The new design & layout technique can improve the SEMU tolerance levels by up to 20 times without sacrificing on area overhead and hence is suitable for high density SRAM designs in commercial applications. Finally, laser testing of SRAM based configuration memory of a Xilinx Virtex-5 FPGA is performed to analyze the behavior of SRAM based systems towards radiation strikes.

The present work reports the study of noncoherent photon upconversion (NCPU) via triplet-triplet annihilation (TTA) in polymer systems. This upconversion mechanism has application in photovoltaic devices through the utilization of sub-band gap photons for potentially enhanced power conversion efficiencies. First, homomolecular TTA was studied in zinc tetraphenylporphyrin (ZnTPP) in polymer matrices. Here, ZnTPP acts as both the sensitizer and upconverting emitter as TTA yields an S2 excited porphyrin. Use of poly(methyl methacrylate) (PMMA) as the host polymer demonstrates aggregation-driven upconverted fluorescence (UC) by TTA (TTA-UC). The dye-loading ratio of the precursor solution was varied, controlling the degree of pre-aggregation. Power-dependence studies of the champion film demonstrated that TTA-UC is occurring toward the strong annihilation kinetic limit. A sub-linear dependence of upconverted fluorescence on film thickness was observed in this system. The ZnTPP study was extended to polymers possessing low glass transition temperatures, representing molecular diffusion-driven TTA-UC. Upconverted fluorescence was not observed in ZnTPP in a polyurethane (PU) matrix, likely due to coordination of the PU to the axial position of the Zn2+ ion. Low intensity NCPU via homomolecular TTA was observed in ZnTPP in a poly(ethylene glycol) (PEG) matrix, but the kinetic limit was not determined due to film photodegradation. Dye-loading studies revealed that porphyrin self-quenching was evident at low dye concentrations. Likely reasons for the low upconverted fluorescence intensities realized are this self-quenching and the possibility of PEG coordination to the Zn2+ ion, though it is believed self-quenching is the dominant parasitic effect. Strategies to determine the effect and extent of polymer coordination to the Zn2+ ion are discussed. The study of polymer-based NCPU is extended to a pair of macromolecules, each containing a single ruthenium tris(bipyridine) (Ru(bpy)3) core and multiple pendant arms, which in turn, each contain eight 9,10-diphenylanthracene (DPA) moieties. A power-dependence study of NCPU in this system is reported, and TTA-UC in the weak annihilation kinetic limit was observed. Upconverted fluorescence quantum yields vary linearly with excitation power in both polymers, consistent with the observed kinetic limit. Stern-Volmer experiments have compared the quenching of Ru(bpy)3 phosphorescence (Ph) by monomeric and polymeric DPA. These data show an enhancement in quenching rate constant for the DPA polymer (pDPA). Kinetic analysis of the Ru-DPA polymers has revealed that the energy scheme realized in this system is intrachain TTET from Ru(bpy)3 core to DPA emitter followed by interchain TTA between excited DPA moieties. Low intensity upconverted fluorescence is observed in Ru-DPA containing thin films. Based on the results presented, the requirements of future photophysically-active polymers are discussed with regards to meaningful application in photovoltaics.

Head Start, an early intervention program administered by the Administration for Children and Families of the Department of Health and Human Services, offers children of low-income families comprehensive services in an effort to even the playing field with their more advantaged peers upon entering kindergarten. Despite the many areas that Head Start addresses, evaluative efforts continuously focus primarily on cognitive gains as a result of Head Start as an intervention. This study examined the potential long-term effects of the health component of Head Start. More specifically, the study investigated whether Head Start impacts a family?s ability to make positive changes in the home in the way of preventive health measures with regard to childhood obesity, immunizations, and dental health, three important areas of childhood health. Participants in the research study included children enrolled in Head Start between 2004 and 2006, and children on the waiting list within the same time. Followup interviews were conducted with families in both groups that inquired about health behaviors specifically related to childhood obesity, immunizations, and dental health. The Head Start (HS) Group and Waiting List Control (WLC) Group were compared to determine if Head Start made a difference in a family?s probability of engaging in more proactive health measures. Responses of the HS Group were also compared with responses from their initial health assessment upon enrolling in Head Start to determine if they demonstrate positive changes. Results did not support hypotheses, and in many instances the WLC Group demonstrated better proactive health measures than the HS Group. Because of operational difficulties, there is limited inference about the impact of the Head Start program. Possible contributors to the results include a small sample size due to the mobility of the target population and overrepresentation of Hispanic children in the study. Limited differences observed between the HS and WLC groups confirms the importance of further investigating the long-term impact of Head Start in areas other than cognitive gains.