Educational and societal demands have drawn much attention to child care issues in America. Two pieces of legislation have had a tremendous impact on many society issues, but none more profoundly than that of center-based child care. Few societal issues have the potential to have such a dramatic impact on the lives of children, especially low-income children, as child care. The awareness of the importance of child care was also heightened by the scientific discoveries of brain development. The overwhelming results of the discoveries in brain development include the nature of learning and the importance of the critical periods in brain development. Scientists have neurological proof that the years before kindergarten are the most important years of development in a child's life. These are the years that a growing number of children, especially low-income children, are spending in child care. Research has documented the importance of early childhood experiences for not only educational achievement but also for adult outcomes. In spite of what is known about child development and the benefits of quality child care for healthy child development, many children do not have access to quality child care services. Although the benefits of quality child care are most evident with low-income children, they are the least likely to receive high quality child care services. The purpose of this study was to gather baseline data on the condition of child care services for low-income children in Mississippi as it existed in 2001. In doing so, the sample consisted of 100 child care centers that participated in the Partners for Quality Child Care Project. This descriptive study collected data using the Early Childhood Environment Rating Scale-Revised, the Infant Toddler Environment Rating Scale, and the Caregiver Interaction Scale. The findings suggested that overall child care for preschools and infant/toddlers was minimal. This level of child care meets the basic standards of health and safety without much opportunity for many developmentally appropriate experiences. However, an investigation of the caregiver interaction as measured by the Caregiver Interaction Scale revealed that there was some evidence that caregivers in 2001 provided care that was warm and supportive.

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<p> We study a many particle system contained within a harmonic oscillator potential, with the single particle spacings equispaced and nondegenerate. We consider either fermions or bosons within this harmonic oscillator potential and derive the density of states for this system, with low excitation energy corrections. We extend our method for more than one species of fermions or bosons within this harmonic oscillator potential and compare our results with number-theoretic techniques. We move on to the degenerate harmonic oscillator potential and show that, for a fermion system, shell effects are contained within low excitation energy terms. We attempt to arrive at the density of states for an infinite number of bosons within the same potential. </p> / Thesis / Master of Science (MSc)

Due to concerns for the environmental and sociological implications of hydrocarbon use, farmers have begun to examine renewable energies and conservation techniques for crop production. Historically, most of the energy needs for climate control in tunnel systems have been met via passive heating, with fossil fuels occasionally providing a supplementary heat source. Five heating techniques were examined for kale (Brassica oleracea) and summer squash (Cucurbita pepo) season extension. Treatments consisted of a low tunnel heated by a solar-powered electrical strip placed under a water tube, a low tunnel heated by a passively heated water tube, a low tunnel heated by an earth-to-air heat-exchange tube, a traditional low tunnel, and a control unprotected plot. Aerogel blankets and SolaWrap® floating covers were also examined as floating covers to protect crops from cold temperatures. To predict energy output, the USDA ARS Virtual Grower was compared against data from the tunneled treatments. Treatments were tested in fall 2020 and spring 2021 with data was collected for air, soil, and tube temperature (ºC), crop growing degree - days, squash seed germination and kale height (cm) and dry biomass (g). The electrically heated water tube produced the highest mean spring day air (28.2 ºC), fall soil temperatures (14.6ºC), thermal tube temperature for the 24 - hour, day and night timeframe for both seasons. However, for soil, the passively heated water tube showed the best results amongst the two seasons heating the soil surface at a 24 - hour mean of 13.8 ºC for fall and 18.2 ºC for spring. The earth tube warmed tunnel air in spring with a mean internal 24 - hour temperature of 19.5 ºC for spring against the 15.7 ºC recorded during fall, while providing the highest mean minimum temperatures. For growing degree-days, all treatments outperformed the uncovered control, with the earth tube treatment performing better for the kale degree day 24 - hour mean of 9.1 for fall 2020 against its spring output of 12.6. The electric heated thermal tube and earth tube improved germination of summer squash during the fall 2020 trial, while the passive tube positively influenced germination during the spring 2021. No differences were observed amongst the treatments in either season for final kale canopy height or dry biomass, though the earth tube displayed the highest range and means. However, kale plants were taller and had greater dry biomass when grown in spring compared to fall. Solar powered heated water tube, earth tube and passively heated water tube accelerated kale development in spring. For the floating cover trial, while the SolaWrap® had the highest mean 24-hour temperature 21.0 ºC, the aerogel blanket showed temperature parity in the daily minimum and night temperatures, and both mean and cumulative kale and summer squash growing degree-days. The Virtual Grower program produced a significantly higher mean and summative kJ output compared to collected by factoring climate, solar radiation, and wind speeds. In the fall study, light limitations arrested kale and squash production rather than a freezing event with treatments being more effective in spring due to increasing daylength. The most effective treatment for spring was the solar powered heated water tube because it provided a first harvestable kale and summer squash at 2-3 whole weeks before conventional spring harvesting, while the earth tube showed a better performance in degree-day accumulation for the cool season kale and warm season squash for the fall extension trial, each having a 24 - hour mean of 9.1 and 12.6. / Master of Science in Life Sciences / Due to both environmental and cost concerns regarding hydrocarbons, farmers have been searching for alternative heating methods to extend the crop season production. At the Virginia Tech Urban Horticulture Center three trials occurred to examine such methods. The first one occurred in spring 2020 and fall 2021 and examined non – hydrocarbon heating methods for low – tunnel systems. Said techniques were a control exposed plot, a simple low – tunnel system, a tunnel that utilized an earth tube, a low – tunnel that had a water tube and a low – tunnel that had a water tube that was warmed by a heating tape powered by solar panels. Crops grown were kale (Brassica oleracea) and summer squash (Cucurbita pepo). Data for this section included mean overall 24 – hour, mean 24 – hour minimum and 24 – hour maximum air temperatures along with mean 24 – hour soil temperatures (oC) with growing degree – days, seed germination, mean seed germination time and kale end season canopy height (cm) and dry biomass (g). The second trial compared the use of aerogels and SolaWrap® as a floating cover against both each other and an exposed plot by looking at their overall 24 – hour, mean 24 – hour minimum and 24 – hour maximum air temperatures. The third section of the trial looked at how the USDA – ARS Virtual Grower Program predicted the required heating output against manual equations from the data gathered in the first part of the trial. For the first section, the best performing systems regarding temperature were the solar powered heating tape due to its ability to store solar energy as well as the earth tube for utilizing a heat source not limited to the presence of the sun. This temperature performance also positively influenced crop germination and development, though the simple water tube also showed better performance. The second section of the trial showed that while the SolaWrap® had a higher overall 24 – hour mean and 24 – hour maximum temperature, the aerogel showed a higher heat retention by having both an equal and higher mean 24 – hour minimum temperature. For the third section, the Virtual Grower showed a higher kJ output requirements due to its ability to factor in location and past climactic activity, something that the manual calculations couldn't do. This trial showed that alternative heating methods, materials and calculations can enhance and extend production, though additional research on both costs and technique optimization are required.

After construction upgrades and implementation of ammonia-based aeration control (ABAC), Hampton Roads Sanitation District's Virginia Initiative Plant (VIP) observed a 69 percent decrease in average dissolved oxygen (DO) concentrations, alongside a 53 percent reduction in average effluent total phosphorus (TP) concentrations from 2019 to 2023. This improvement in effluent quality coincided with the elimination of metal salt addition in 2023. Batch tests conducted from 2020 to 2024 indicated higher phosphorus release and aerobic uptake rates at lower DOs, even at higher temperatures, while 16S rRNA amplicon sequencing analysis suggested a community shift toward polyphosphate-accumulating organisms (PAOs). Statistical analysis revealed that low DO operation (DO concentrations below 1 mg O2/L) did not negatively impact effluent TP concentrations and were positively correlated with increased PAO abundance. High rates of denitrification fueled by internally stored carbon in the post-anoxic zone were found to co-occur with elevated PAO activity, and subsequent batch tests indicated post-anoxic phosphorus uptake rates ranging from 3 to 40 percent of the aerobic phosphorus uptake rates. Removing the aerobic phase in batch tests increased both anoxic phosphorus uptake and denitrification utilizing internally stored carbon. This emergence of post anoxic phosphorus uptake capacity is potentially attributable to the reduction in DO concentrations. The reduction in average aerobic SRT from 8.5 ± 0.4 days in 2021 to 5.7 ± 0.1 days in 2023 was significantly correlated with improved effluent phosphorus quality. An aerobic phosphorus uptake online analyzer at full-scale was demonstrated as an effective tool to indirectly monitor the health of the PAO population and provide continuous data for real time process optimization. Understanding the conditions that improve EBPR at full-scale is important to achieve more stringent phosphorus limits that are anticipated in the future. Implementing the above strategies can reduce aeration energy consumption, metal salt and external carbon requirements, and environmental footprints at WRRFs. / Master of Science / Excess amounts of phosphorus discharged into aquatic ecosystems can lead to eutrophication, a process where algal blooms deplete the oxygen needed for other aquatic life, resulting in large scale mortalities. Water Resource Recovery Facilities (WRRFs) employ chemical, biological and/or physical means to remove phosphorus from discharged water to prevent eutrophication. Enhanced biological phosphorus removal (EBPR) is a process that takes advantage of microorganisms known as polyphosphate-accumulating organisms (PAOs) to remove phosphorus from the water. PAOs can store high amounts of phosphorus in their biomass when they are subjected to alternating anaerobic and aerobic conditions. The phosphorus is then removed with the PAOs by settling and wasting the biomass. The conventional operational approach at WRRFs is to maintain an aerobic phase with dissolved oxygen (DO) concentrations above 2 mg O2/L to maximize phosphorus uptake. However, Hampton Roads Sanitation District's Virginia Initiative Plant (VIP) observed a 69 percent decrease in average DO concentrations, alongside a 53 percent improvement in effluent phosphorus quality from 2019 to 2023. Batch tests conducted from 2020 to 2024 indicated higher phosphorus release and aerobic uptake rates at lower DO concentrations, while microbial analysis revealed a community shift toward PAOs. Recent batch tests conducted in 2023 indicated phosphorus uptake rates in the anoxic phase that ranged from 3 to 40 percent of the phosphorus uptake rates in the aerobic phase. This emergence of anoxic phosphorus uptake capacity is potentially attributable to the reduction in DO concentrations. These results highly suggest that low DO operation (DO concentrations below 1 mg O2/L) does not negatively impact EBPR performance. In fact, low DO concentrations were positively correlated with increased PAO abundance. Low DO operation can reduce aeration energy consumption, operational costs, and environmental footprints of WRRFs. Furthermore, VIP implemented other operational strategies to optimize EBPR and monitor PAO activity, including an aerobic phosphorus uptake online analyzer. This analyzer was demonstrated as an effective tool to indirectly monitor the health of the PAO population and provide continuous data for real time process optimization.

Ultra-Wideband (UWB) technologies are at the forefront of wireless communications, offering the possibility to provide extremely high data rate wireless solutions. In addition to high data rate applications, UWB technologies also offer an extremely low cost alternative for many low data rate systems. In this thesis, we describe the design of a CMOS pulse generator for impulse based UWB systems. The structure of our pulse generator is based on the topology of a single tap CMOS power amplifier. By increasing the number of taps on a CMOS power amplifier, it is possible to generate sub-nanosecond pulses with a desired shape. A power saving scheme that significantly reduces the power consumed at low data rates is also described. The versatility of our design lies in the ability to support dynamically varying output power levels and center frequencies. Our pulse generator design is extended to a rectified cosine generator, necessary for a multiband approach. The performance of our pulse generators is estimated through simulation with a target technology of TSMC 0.18 µm CMOS at a supply voltage of 1.8 V. The simulation results indicate that our pulse generator produces high fidelity Gaussian monocycle pulses with a pulse width of approximately 160 ps and a peak output power of more than 10 mW. We believe that our design of a CMOS pulse generator for UWB systems is a feasible option for many applications in which power and cost are most important. / Master of Science