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The purpose of the study was to identify student summer activities and determine whether a relationship exists between the activities and mathematics testing change scores measured from spring to fall. This current effort built upon research conducted by Heyns (1978), Burkam et al. (2004), Downey et al. (2004), and Alexander et al. (2007). The commonality in findings that existed among all of these efforts was that learning loss occurred in the absence of instruction such as that experienced during the normal school term. A quantitative, correlational study was conducted using a survey method which requested that parents answer questions concerning the nature of activities and daily structure experienced by their children during the summer break. The Group Mathematics Assessment and Diagnostic Evaluation (GMADE) testing platform was used to generate quantitative measurements of mathematics skills for exiting second graders in the spring of 2010 and for these same students as entering third graders in the fall of 2010. A voluntary sample of 57 students from elementary schools in a suburban school district in Southwestern Virginia participated in the testing process. At the conclusion of all testing and at the point at which all surveys were completed, student scoring differentials from spring to fall were compared to the activity and daily structure components reported in the survey for potential correlations between that information and mean gain test results. This study sought potential correlations between types of summer activities and documented change between mathematics spring and fall test scores. Results of data analysis from this research will assist leaders in understanding whether activities bear a relationship to mathematics score changes. Should those relationships be established, the findings would assist leaders in determining which activities should be encouraged or discouraged during the summer break to avoid score declines. The findings indicated that though summer mathematics learning loss did occur for the participants, no correlation between activities and test score change could be established. Implications of these findings and suggestions for the future are presented in the final chapter. / Ed. D.

While the idea of critical break rate of water distribution pipeline (defined as the break rate after which it is no longer economical to continuously repair) has been accepted in the literature and among the practicing engineers, the formula to obtain the critical break rate has remained elusive. In this dissertation, an equation for identifying the threshold break rate of a pipe is developed. The threshold break rate equation gives a rule of thumb for pipe replacement decision. Input parameters to obtain the threshold break rate of a pipe are repair and replacement costs, interest rate, and the length of the pipe. In addition, a methodology that enables the use of threshold break rate with the failure intensity and hazard functions is developed. The methodology is drawn by considering the relationships of the definitions of the threshold break rate with intensity and hazard functions in the context of a repairable system's failure process modeling. As a result, the newly developed threshold break rate equation can be coupled with any appropriate intensity and hazard function to obtain economically optimal replacement time of a pipe. Also, practical usage of the threshold break rate is demonstrated with a number of numerical examples. Design aids in the form of charts and tables are provided. The threshold break rate can be easily obtained either graphically or with the aid of the tables. The methodology that links the threshold break rate and failure rate (intensity and hazard) functions is extended to accommodate stress multiplying environmental factors in the form of the proportional intensity and hazards model. The two models consist of an age dependent failure rate function and a covariate structure. They are applied to a case study area pipe system to obtain optimal replacement times for individual pipes in the system. As a result, important hazard characteristics of water distribution pipes are drawn, and implications on the optimal replacement analysis are discussed. A pipe break prediction model is also developed in this research. The model spans the space between the linear and exponential break trends. The model is applied to the case study area pipe system with various cost options. The results from this analysis are discussed in terms of practical implementation of the replacement strategies. / Ph. D.

Yes / Large amount of sediment deposits in the reservoir area can cause dam break, which not only leads to an immeasurable loss to the society, but also the sediments from the reservoir can be transported to generate further problems in the downstream catchment. This study aims to investigate the short-to-long term sediment transport and channel meandering process under such a situation. A coupled explicit-implicit technique based on the Euler-Lagrangian method (ELM) is used to solve the hydrodynamic equations, in which both the small and large time steps are used separately for the fluid and sediment marching. The main feature of the model is the use of the Characteristic-Based Split (CBS) method for the local time step iteration to correct the ELM traced lines. Based on the solved flow field, a standard Total Variation Diminishing (TVD) finite volume scheme is applied to solve the sediment transportation equation. The proposed model is first validated by a benchmark dambreak water flow experiment to validate the efficiency and accuracy of ELM modelling capability. Then an idealized engineering dambreak flow is used to investigate the long-term downstream channel meandering process with nonuniform sediment transport. The results showed that both the hydrodynamic and morphologic features have been well predicted by the proposed coupled model. / This research work is supported by Sichuan Science and Technology Support Plan (2014SZ0163), Start-up Grant for the Young Teachers of Sichuan University (2014SCU11056), and Open Research Fund of the State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University (SKLH 1409; 1512).

Wavelet intensity based algorithm developed previously at VirginiaTech has been furthered and paired with an SVM based classifier. The wavelet intensity algorithm acts as a feature extraction algorithm. The wavelet transform is an effective tool as it allows one to narrow down upon the transient, high frequency events and is able to tell their exact location in time. According to prior work done in the field of signal processing, the local regularities of a signal can be estimated using a Lipchitz exponent at each time step of the signal. The local Lipchitz exponent can then be used to generate the wavelet intensity factor values. For each vertical acceleration value, corresponding to a specific location on the track, we now have a corresponding intensity factor. The intensity factor corresponds to break-no break information and can now be used as a feature to classify the vertical acceleration as a fault or no fault. Support Vector Machines (SVM) is used for this binary classification task. SVM is chosen as it is a well-studied topic with efficient implementations available. SVM instead of hard threshold of the data is expected to do a better job of classification without increasing the complexity of the system appreciably. / Master of Science

The Central Atlantic Magmatic Province (CAMP) is the large igneous province (LIP) that coincides with the breakup of the supercontinent Pangea. Major and trace element data, Sr-Nd-Pb radiogenic isotopes, and high-precision olivine chemistry were collected on primitive CAMP dikes from Virginia (VA). These new samples were used in conjunction with a global CAMP data set to elucidate different mechanisms for supercontinent breakup and LIP formation. On the Eastern North American Margin, CAMP flows are found primarily in rift basins that can be divided into northern or southern groups based on differences in tectonic evolution, rifting history, and supercontinental inheritance. Geochemical signatures of CAMP suggest an upper mantle source modified by subduction processes. We propose that the greater number of accretionary events, or metasomatism by sediment melts as opposed to fluids on the northern versus the southern Laurentian margin during the formation of Pangea led to different subduction-related signatures in the mantle source of the northern versus southern CAMP lavas. CAMP samples have elevated Ni and low Ca in olivine phenocrysts indicating a significant pyroxenite component in the source, interpreted here as a result of subduction metasomatism. Different collisional styles during the Alleghanian orogeny in the North and South may have led to the diachroneity of the rifting of Pangea. Furthermore, due to a low angle of subduction, the Rheic Plate may have underplated the lithosphere then delaminated, triggering both the breakup of Pangea and the formation of CAMP. / Master of Science

Aedes aegypti transmits the viruses which cause yellow fever, dengue fever, and dengue hemorrhagic fever. Homing endonucleases are selfish genetic elements which introduce double-stranded DNA (dsDNA) breaks in a sequence-specific manner. In this study, we aimed to validate a somatic assay to detect recombinant homing endonuclease (rHE)-induced dsDNA breaks in both cultured cells and adult female Ae. aegypti. While the cell culture-based two plasmid assay used to test rHE ability to induce dsDNA breaks was inconclusive, assays used to test rHEs in Ae. aegypti were successful. Recognition sequences for various rHEs were introduced into Ae. aegypti through germline transformation, and imperfect repair at each of these exogenous sites was evaluated. In mosquitoes containing a single exogenous HE site, imperfect gap repair was detected in 40% and 21% of clones sequenced from mosquitoes exposed to I-PpoI and Iâ SceI, respectively. In mosquitoes containing two exogenous HE sites flanking a marker gene (EGFP), 100% of clones sequenced from mosquitoes exposed to I-PpoI, I-CreI, and I-AniI demonstrated excision of EGFP. No evidence of EGFP excision or imperfect repair at any HE recognition site was detected in mosquitoes not exposed to a rHE. In summary, a somatic genomic footprint assay was developed and validated to detect rHE or other meganuclease-induced site-specific dsDNA breaks in chromosomal DNA in Ae. aegypti. / Master of Science in Life Sciences

No / An incompressible smoothed particle hydrodynamics (SPH) method is presented to simulate Newtonian and non-Newtonian flows with free surfaces. The basic equations solved are the incompressible mass conservation and Navier¿Stokes equations. The method uses prediction¿correction fractional steps with the temporal velocity field integrated forward in time without enforcing incompressibility in the prediction step. The resulting deviation of particle density is then implicitly projected onto a divergence-free space to satisfy incompressibility through a pressure Poisson equation derived from an approximate pressure projection. Various SPH formulations are employed in the discretization of the relevant gradient, divergence and Laplacian terms. Free surfaces are identified by the particles whose density is below a set point. Wall boundaries are represented by particles whose positions are fixed. The SPH formulation is also extended to non-Newtonian flows and demonstrated using the Cross rheological model. The incompressible SPH method is tested by typical 2-D dam-break problems in which both water and fluid mud are considered. The computations are in good agreement with available experimental data. The different flow features between Newtonian and non-Newtonian flows after the dam-break are discussed.