The large thermal cross section of cadmium makes it ideal for many practical applications where screening of thermal neutrons is desired. For example, in non-destructive assay techniques, or for astrophysical studies of the s-process. All such applications require precise knowledge of the neutron-capture cross section on cadmium. Although there are some data on neutron-capture cross sections particularly at thermal energies and at energies relevant for astrophysics, there is very little data at most other energies. Further, the evaluated cross sections from the ENDF and JENDL databases disagree at high energies. Therefore, there is a critical need for precise knowledge of the 114Cd(n, gamma)115Cd cross section over a large range of incident neutron energies. We performed a direct measurement of the neutron-capture cross section at the Los Alamos Neutron Science Center (LANSCE) using the Detector for Advanced Neutron Capture Experiments (DANCE). A highly enriched (∼$99%), 100 mg pressed metallic pellet sample of 114Cd was used to perform the neutron-capture measurements in the range of 1 eV to 300 keV using the white neutron source available at LANSCE. Additional neutron capture data were also taken on highly enriched samples of 112Cd and 113Cd to enable careful background subtraction of even the small contaminants found in the 114Cd sample. We used a large energy sum windows around the Q-value to circumvent any complication that may arise from populating the 180 keV isomeric (T1/2 = 44.56d) state in 115Cd.

Osteopathic Manipulative Treatment (OMT) has been used for more than 100 years to enhance the physiologic process of labor and delivery by normalizing pelvic structures and providing adequate blood supply to the uterus. Since maternal morbidity and mortality is a major health concern for developing countries, it was desirable to explore the benefits of OMT. After IRB approval by the Virginia College of Osteopathic Medicine and Virginia Tech, the research was conducted in Santo Domingo, Dominican Republic at Hospital Maternidad Nuestra Señora de la Altagracia to determine the relationship of OMT during labor and delivery on rates of cesarean section and perineal lacerations/ episiotomies. Qualifying candidates received the next sequentially numbered envelope with a randomized number assigning her to either the treatment or control group. Staff physicians at the hospital provided care to women in the control group according to their standard protocol. Four Osteopathic Physicians and one pre-doctoral OMM fellow performed OMT on women during the first and second stages of labor and performed their deliveries. There were 33 parturients in the OMT Treatment group and 32 in the control, for a total of 65 in the trial. The results of a logistic regression analysis using Wald criterion, with a statistical significance of alpha = 0.05, indicated treatment group reduction of rates of episiotomies in the primiparous (P = .04) and marginal significance in the combined primiparous and multiparous population (P = .05). The percentage of episiotomies in the primiparous treatment group was 35.29% and 75% in the control group. The percentage of episiotomies in the combined primiparous and multiparous groups were 15.15% in the treatment group and 37.5% in the control group. The cesarean rate for the treatment group was 9.09% and 18.75% for the control group (P = 0.098). The percentages of grade I & II perineal lacerations were 15.15% for the treatment group and 12.5% for the control group (P = 0.55) due to the extensive use of episiotomies in the control group. There were composite calculations made of the total number of parturients who had either a cesarean section, an episiotomy, or a perineal laceration so that overall maternal morbidity in each group could be compared. In the combined groups, there were fourteen total parturients (42.42%) who had undergone one of the three outcomes measures in the treatment group and twenty-one (65.63%) in the control group. This brings an odds ratio of 0.200 and a significant P value of 0.0235. Though cross-cultural issues made it difficult to perform the research as originally intended, there is evidence that Osteopathic Obstetrics provides benefit to parturients. A multi-institutional randomized controlled trial is proposed as the next step for the evaluation of OMT during labor and delivery. / Ph. D.

Congress continues to prefer nonprofit organizations over government and for-profit investors for participation in federally assisted multifamily housing programs because nonprofit organizations are believed to be more efficient in delivering services than government and more altruistic than for-profit investors. However, empirical information to support these beliefs is limited. The purpose of this study was twofold: a) to determine if property management practices of federally assisted, nonprofit-owned multifamily housing properties are different from those of comparable government- and for-profit-owned properties with regard to administration practices, financial management practices, maintenance procedures, and services provided to residents and b) to determine how much variance in these management practices is explained by type of owner, owner's goals for property , property manager's qualifications, and neighborhood environment. Independent t-tests and a multiple regression analysis, respectively, were used. The population consisted of public housing and Section 8 nonprofit- and for-profit-owned, project-based properties in Virginia (197 properties total). Results were based on 96 property managers’ responses to an 81-item mailed questionnaire, which included open- and close-ended responses. Management practices at the nonprofit-owned properties generally were not significantly different (at .10 alpha level) from those at either the government- or for-profit- owned properties. Nonetheless, some patterns were apparent. These included the nonprofit-owned properties having lower vacancy and unit turnover rates, quicker turnaround times for routine maintenance, and more initiatives to empower residents than the for-profit-owned properties. Also, management at the nonprofit-owned properties tended to conduct their maintenance more frequently and quickly than management at the government-owned properties. Approximately 42% of the variability in the management practices of the sample was explained by type of owner, owner’s goals for property, property manager’s qualifications, and neighborhood environment. Moreover, the nonprofit-owned properties, on average, scored higher than the government- and for-profit-owned properties with regard to their overall property management practices. While these findings appear to support Congress’ preference of nonprofit organizations over government and for-profit investors for participation in federally assisted multifamily housing programs, concern exists about the financial solvency of the nonprofit-owned properties, particularly since one-third of these properties failed to meet budget goals. / Ph. D.

Short, J-section columns fabricated from a textile composite are tested in axial compression to study the modes of failure with and without local buckling occuring.The textile preform architecture is a 2x2, 2-D triaxial braid with a yarn layup of [0 deg 18k/+-64 deg 6k] 39.7% axial. The preform was resin transfer molded with 3M PR500 epoxy resin. Finite element analyses (FEA) of the test specimens are conducted to assess intra- and inter- laminar progressive failure models. These progressive failure models are then implemented in a FEA of a circular fuselage frame of the same cross section and material for which test data was available. This circular frame test article had a nominal radius of 120 inches, a forty-eight degree included angle, and was subjected to a quasi-static, radially inward load, which represented a crash type loading of the frame. The short column test specimens were cut from some of the fuselage frames. The branched shell finite element model of the frame included geometric nonlinearity and contact of the load platen of the testing machine with the frame. Intralaminar progressive failure is based on a maximum in-plane stress failure criterion followed by a moduli degradation scheme. Interlaminar progressive failure was implemented using an interface finite element to model delamination initiation and the progression of delamination cracks. Inclusion of both the intra- and inter- laminar progressive failure models in the FEA of the frame correlated reasonably well with the load-displacement response from the test through several major failure events. / Master of Science

a series of sectional graphics are created to represent the architectural whole. this thesis is about how a three dimensional architecture is seen and perceived through use of two dimensional graphics. it is about understanding a finished work [the whole] by viewing its individual sectional layers [the parts]. a whole does not exist without its parts, just as architecture would not exist without section. in this case, the section is raised above all other things in order to see the potential of the whole. / Master of Architecture

This work presents a detailed predictive modeling methodology for comprehensive crashworthiness analysis of advanced jet engine forward sections, containing hybrid and composite structures, when subjected to soft impact. Bird strike onto the fan assembly is chosen as the impact event to be studied. The aim is to develop a numerical methodology capable of accurately capturing the full range of multifaceted damage in hybrid and composite structures as they evolve throughout the forward section of a propulsion system. Effective strategies are developed within an explicit finite element framework for modeling a bird, an engine forward section, intra-ply and inter-ply composite damage, and hybrid structural failure. The accuracy of each approach and their numerical modeling considerations are thoroughly investigated. These techniques are then combined to form the full crashworthiness methodology. It is demonstrated that the complete methodology effectively captures progressive hybrid fan blade fracture, leading edge de-bonding, composite casing delamination, and other significant progressive damage effects caused by direct impact and subsequent engine component interactions. The full damage prognosis capabilities demonstrated by this approach encompass aspects which have remained mainly unaddressed in soft impact analysis. A methodology for assessing the complete extent of impact damage for advanced structural engine designs represents a breakthrough that can contribute greatly to the rapid development of these systems in the future. / Master of Science

During an earthquake, columns in a one-story building must support vertical gravity loads while undergoing large lateral drifts associated with deflections of the vertical seismic force resisting system and deflections of the flexible roof diaphragm. Analyzing the behavior of these gravity columns is complex since not only is there an interaction between compression and bending, but also the boundary conditions are not perfectly pinned or fixed. In this research, the behavior of steel columns that are square hollow structural sections (HSS) is investigated for stability using three design methods: elastic design, plastic hinge design, and pinned base design. First, for elastic design, the compression and flexural strength of the HSS columns are calculated according to the AISC specifications, and the story drift ratio that causes the interaction equation to be violated for varying axial force demands is examined. Then, a simplified design procedure is proposed; this procedure includes a modified interaction equation applicable to HSS column design based on a parameter, Pnh/Mn, and a set of design charts are provided. Second, a plastic hinge design is grounded in the concept that a stable plastic hinge makes the column continue to resist the gravity load while undergoing large drifts. Based on the available test data and the analytical results from finite element models, three limits on the width to thickness ratios are developed for steel square HSS columns. Lastly, for pinned base design, the detailing of a column base connection is schematically described. Using FE modeling, it is shown that it is possible to create rotational stiffness below a limit such that negligible moment develops at the column base. All the design methods are demonstrated with a design example / Master of Science / One-story buildings are one of the most economical types of structures built for industrial, commercial, or recreational use. During an earthquake, columns in a one-story building must support vertical gravity loads while undergoing large lateral displacements, referred to as story drift. Vertical loads cause compression forces, and lateral drifts produce bending moments. The interaction between these forces makes it more complex to analyze the behavior of these gravity columns. Moreover, since the column base is not perfectly fixed to the ground, there are many boundary conditions applicable to the column base depending on the fixity condition. For these reasons, the design for columns subjected to lateral drifts while supporting axial compressive forces has been a growing interest of researchers in the field. However, many researchers have focused more on wide-flange section (I-shape) steel columns rather than on tube section columns, known as hollow structural section (HSS) steel columns. In this research, the behavior of steel square tube section columns is investigated for stability using three design methods: elastic design, plastic hinge design, and pinned base design. First, for elastic design, the compression and flexural strength of the HSS columns are calculated according to current code equations, and the story drift that causes failure for varying axial force demands is examined. Then, a simplified design procedure is proposed including design charts. Second, a plastic hinge design is grounded in the concept that controlled yielding at the column base makes the column continue to resist the gravity load while undergoing large drifts. Based on the available test data and results from computational models, three limits on the width to thickness ratios of the tubes are developed. Lastly, for pinned base design, concepts for detailing a column base connection with negligible bending resistance is schematically described. Using a computational model, it is shown that the column base can be detailed to be sufficiently flexible to allow rotation. All the design methods are demonstrated with a design example.

There is a present and future need for the medical isotope Actinium-225, currently in short supply worldwide.  Only a couple manufacturers produce it in very low quantities.  In roughly the past 10 years the medical community has explored the use of Ac-225 and its daughter Bismuth-213 for targeting a number of differing cancers by way of Targeted Alpha Therapy (TAT). This method utilizes the alpha-decay of both Ac-225 (half-life 10 days) and Bi-213 (half-life 46 min) to kill cancerous cells on a localized basis.  Maximum energy is delivered to the cancer cells thereby greatly minimizing healthy tissue damage. This research proposes a production method using a high-energy photon spectrum (generated by a linear accelerator or LINAC) to irradiate a sample of Radium-226 (half-life 1600yrs).  The photo-neutron reaction liberates neutrons from Ra-226 atoms leaving behind Radium-225 (half-life 14.7 days).  Ra-225 decays naturally through beta emission to Ac-225.  Previous research demonstrated it is possible to produce Ac-225 using a LINAC; however, very low yields resulted which questioned the feasibility of this production method.  This research proposes a number of LINAC and radium sample modifications that could be greatly increase yield amounts for practical use. Additionally, photo-neutron cross-section data for Ra-226 was used, which led to improved yield calculations for Ra-225.  A MATLAB® model was also created, which enables users to perform quick yield estimates given several key model parameter inputs.  Obtaining a sufficient supply of radium material is also of critical importance to this research.  Therefore information was gathered regarding availability and inventory of Radium-226.  This production method would serve as a way to not only eliminate many hazardous radium sources destined for interim storage, but provide a substantial supply of Ac-225 for future cancer treatment. / Master of Science

Future long baseline neutrino oscillation experiments like the Deep Underground Neutrino Experiment (DUNE) rely on Liquid Argon Time Projection Chamber (LArTPC) detectors. The reconstruction of neutrino flavors and energy through interactions with Argon is a critical issue for assuring the DUNE success. The neutrino-Argon nuclear cross section is one of the biggest sources of uncertainty in measuring possible Charge-Parity Violation (CPV) in the neutrino (ν) sector and decoupling background like matter-effects. This thesis summarizes the exclusive electron scattering measurement of the Jefferson Lab E12-14-012 experiment. The E12-14-012 experiment goals are to explore the Ti(e,e′p) and Ar(e,e′p) reactions in a wide range of kinematics in order to determine the spectral function of protons and neutrons in Argon. The measurements made in E12-14-012 are the first of their kind in argon and are a pivotal step in understanding the electron-Argon interaction and its relation to neutrino scattering. Titanium was specifically chosen under an assumption that its protons can be a proxy for argon neutron spectral functions. The analysis of the exclusive electron scattering in titanium is described in detail in this thesis. / M.S. / While considerable progress has been made in understanding the power of the atom, nucleons (protons and neutrons) trapped in medium-to-heavy nuclei have properties that we still need to understand. The purpose of this thesis is to explore the nuclear investigation conducted at Jefferson Lab (JLab) in Newport News, Virginia. Specifically, we follow the data analysis of the JLab Hall A Experiment E12-14-012 which seeks to quantify the nuclear energy momentum distributions of nucleons in complex nuclei like titanium and argon. These measurements, the first of their kind experimentally, are done to provide a reliable model for lepton-nucleus interactions. Modeling lepton-nucleus interactions in argon is of paramount importance, as argon is the primary target medium in future long baseline neutrino oscillation experiments like DUNE. Neutrinos are notoriously difficult to measure; and therefore, when they interact, we only measure the interaction products as they come out of the nucleus. Sometimes the products of the primary interaction will not escape the nucleus and have to be modelled to accurately estimate the incoming neutrino energy. The analysis on titanium provided in this thesis is a bridge for argon interactions with leptons, where titanium is used to determine argon neutron momentum and energy distributions.

Steel moment frames are a popular seismic-force resisting system, but it is believed that they are susceptible to early fracture if there is a stress concentration in the plastic hinge region, also known as the protected zone. If a defect is present in this area, it may be repaired by grinding and/or welding, but little research has investigated how the repairs affect the performance of full-scale moment connections subjected to inelastic rotations. Thus, the goals of this research were to establish the performance of full-scale moment connections with repairs and defects, then develop a method for predicting fracture of the full-scale specimens using more economical cyclic bend tests. To do this, six full-scale reduced beam section (RBS) connections were tested having arrays of repairs or defects applied to the flanges. The repairs were 0.125 in. deep notches ground to a smooth taper and 0.25 in. deep notches ground to a smooth taper, welded, and ground smooth. The defects were sharp 0.25 in. and 0.375 in. notches. In addition, 54 bend tests were conducted on beam flange and bar stock coupons having the same repairs and defects, power actuated fasteners, puddle welds, and no artifacts. Finally, Coffin-Manson low-cycle fatigue relationships were calibrated using results from the cyclic bend tests with each artifact (repair, defect, or attachment method) and used in conjunction with estimates of full-scale plastic strain amplitudes to predict fracture of full-scale specimens. All four of the full-scale moment connections with repairs satisfied special moment frame qualification criteria (SMF). One full-scale specimen with sharp 0.25 in. notches satisfied SMF qualification criteria, but the flexural resistance dropped rapidly after the qualification cycle. On the other hand, the specimen with sharp 0.375 in. notches did not satisfy SMF qualification criteria due to ductile fractures propagating from the notches. The proposed method for predicting fracture of full-scale connections was validated using the six current and six previous full-scale RBS specimens. This method underpredicted fracture for eleven of the twelve specimens. The ratio of the actual to predicted cumulative story drift at fracture had a mean of 1.13 and a standard deviation of 0.19. / M.S. / Moment connections in steel structures resist earthquake loads by permanently deforming the material near the connection. This area is called the protected zone and is critical to the safety of the structure in an earthquake. Due to this importance, no defects are allowed near the connection, which can include gouges or notches. If a defect does occur, it must repaired by a grinding or welding. These are the required repair methods, but there have be no tests to determine how the repairs affect the strength and ductility of the connection. This research tested six full-scale moment connections with defects repaired by grinding and welding, as well as unrepaired defects. A correlation was also developed and validated between the full-scale tests and small-scale bend tests of steel bars with the same defects and repairs. This relationship is valuable because the small-scale tests are quicker and less expensive to conduct than the full-scale tests, meaning other defects or repairs could be easily tested in the future. All but one of the six full-scale specimens met the strength requirements and had adequate ductility. The one test specimen that failed had an unrepaired defect. The relationship between the full-scale and small-scale tests underpredicted fracture (a conservative estimate) for the five of the full-scale tests and overpredicted fracture (unconservative estimate) for one test.