Research on stepfamily life in the 21st century reveals unexplored variables at every turn. This is important because around half of American adults report close step-relationships and the challenges and demographic and relational differences for different types of stepfamilies remains unexplored. The first of these studies explored data for 879 husbands and wives couples to explore how positivity, negativity, and sexual interest levels differ depending which of the couple, both partners, or neither had previous children. Wives reported higher levels of marital instability and positivity than husbands. Marital instability was linked with one’s own and one’s partners’ negativity, and inversely related to one’s own and one’s partners’ positivity and sexual interest. The marital instability of those with children was related with their partner’s negativity. The second study investigated how the marital stability of different stepfamily configurations is related to difficulties associated with the social and family dimension, the role of the spouse, the role of a parent, and the role of a stepparent. Wives’ scores of marital instability and difficulties being a parent and stepparent were higher than husbands’ across remarriage types. Stepmothers reported the highest levels of parenting and stepparenting strain, especially stepmothers without children of their own. This implies stepfamily challenges can impact family-related stress and marital instability, with the most profound effects found for stepmothers with no biological children of their own. We found that parents with children seem to be sensitive to negativity and sexual interest from their partners as a measure of relationship functioning. Stepmothers experienced higher levels of marital instability and difficulties associated with being a parent and a stepparent and this is especially true for stepmothers who did not have children of their own. These findings suggest couples may benefit from strategies that decrease negativity, increase positivity and sexual interest, and help manage the stresses associated with being a parent and stepparent, especially for stepmothers

This thesis develops a method to analyze the roll response of a vessel during a damaged (flooded) scenario. This was done by developing a time-domain method in which the damaged compartment was flooding while the ship is simultaneously subjected to a seaway. The KRISO containership was used as a test hull and was subjected to three flooding conditions. These flooding conditions involved flooding Hold 5, Hold 3, and Hold 1 separately. Newmark’s Beta method for linear acceleration was used to solve the roll motion of equation in which the hydrodynamic coefficients A44, B44, and C44 were predetermined from linear strip theory for various drafts and trim angles. The roll response in the transient flooding state and the steady state, after flooding ceased (fully damaged state), while in wave action was simulated and plotted. The amplitudes from the initial and damaged steady states were recorded at the given wave frequency and wave amplitude, to generate the roll response amplitude operators for the vessel from wave frequency ω = 0.1 rad/s to ω = 2.1 rad/s. Analysis of the RAO curves revealed that the KRISO was not made significantly more unstable by the flooding, for the conditions that were considered, for nearly all wave frequencies except the natural frequency of 0.5 rad/s.

The coupled effect of using geosynthetic reinforcement and randomly distributed fibers on the stability of slopes was evaluated using finite element modeling and limit equilibrium methods by analyzing a case study in Oslo, Norway. The main objective was to simulate the failure condition of the original slope and quantify the improved stability of a hypothetical reinforced slope constructed with geosynthetic layers and distributed discrete fibers. The stability of the slope was evaluated in both the short-term condition with its' undrained shear strength parameters, and the long-term drained condition. Results indicate that the combination of the techniques was found to have a possible increase of about 40% in the short-term condition and about 60% in the long-term condition of the factor safety associated with the slope. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2019. / FAU Electronic Theses and Dissertations Collection

The stability criteria for single-mode standing-wave laser oscillators in the strongly homogeneously broadened limit are reported for the first time. Two types of stability criteria are presented. The first type, called type 1, corresponds to the minimum value of threshold parameter for which an infinitesimal perturbation away from steady state grows into an oscillatory solution. Another type of stability criteria, called type 2, corresponds to the minimum value of threshold parameter for which large amplitude oscillatory solutions do not decay to the steady state solution. Undamped pulsations in single mode strongly homogeneously broadened standing-wave laser oscillators are found to occur at a much higher excitation level than that of ring-laser oscillators with the same type of line broadening. The effect of detuning on stability criteria is also investigated. We discovered that detuning tends to raise the type 1 instability threshold and to decrease the type 2 instability threshold.

Thesis (M.Sc. (Physics)) -- University of Limpopo, 2015 / While the effect of sulphur on c-ZrO2 is often considered in application of advanced solid oxide fuel cells and biomass gasification cleanup, there has been little study on the effect of sulphur on general structure of c-ZrO2. In this work a study of the structural, energetic, electronic and elastic properties of doped c-ZrO2-xSx, t-ZrO2xSx and m-ZrO2-xSx solid solutions has been carried out using ab-initio total energy calculation of the density functional theory under plane wave pseudopotential method within generalized gradient approximation using the self-consistent virtual crystal approximation (VCA). It has been shown that all the calculated properties obtained after relaxation are in good agreement with available experimental and other calculated values, particularly at x=0. Furthermore, the formation and cohesive energies were calculated to determine the relative stability of all three non-sulphated and sulphated polymorphs of ZrO2. The density of states and band structures have been computed for x = 0.0 - 0.5, and the actual size of the band gap of ZrO2 compounds narrowed with partial replacement of oxygen by sulphur, while peaks above Fermi level move towards the Fermi level. The material changes its insulating properties to semiconductor material as a function of sulphur concentration, which might be useful for potential application. We also investigated and calculated, for the first time, the effect composition variation on mechanical stability, the independent elastic constants and other elastic parameters of the sulphated compounds. The polycrystalline bulk moduli, shear moduli, Young and Poisson’s ratio have been deduced by using Voight-Reuss-Hill (VRH) approximation. In addition we also show the geometric and electronic structure of pure ZrOS and ZrS2 and compare them with the obtained geometric and electronic structures of ZrO2-xSx.

Friendships are an important context of children's development, yet there is much still to be learned about these formative relationships. Friendship stability is one understudied feature of children's friendships. The aim of the present study was to investigate both predictors and outcomes associated with friendship stability to further elucidate the role that friendships play in shaping children's development. Potential predictors examined included age, gender, gender match, race, residence in a rural or urban community, number of moves in the last year, child externalizing behavior, friendship quality, and deficient parenting. Similarity between friends in terms of overt and relational aggression was also examined as a potential predictor of stability, and age was tested as a potential moderator of these relations. Additionally, a double mediational model was explored wherein child behavior was tested as a mediator of the link between deficient parenting and friendship quality and friendship quality was tested as mediator of the link between child behavior and friendship stability. Finally, in order to better understand the impact of stable friendships on children's adjustment, the present study tested friendship stability as a predictor of time 2 child externalizing behavior after controlling for time 1 externalizing behavior. Participants were 176 children and primary caretakers enrolled in a 3-year longitudinal study examining the social development of children living in circumstances of social disadvantage. A multisource, multimethod approach was used to assess deficient parenting and children's externalizing behavior. Friendship stability was assessed over two waves approximately 12 months apart. Participating children provided data on their friendships, friendship quality, and friends' aggressive behavior. Children were invited to report on friendships occurring in any setting and friendship stability was examined both in children's networks of 1-3 best friends and in children's relationships with one very best friend. Proposed models were tested using structural equation modeling. The link between child externalizing behavior and friendship stability was supported, as was the link between deficient parenting and child externalizing behavior. Deficient parenting and friendship quality did not predict friendship stability. Thus, the role of child externalizing behavior as a mediator of the relation between deficient parenting and friendship stability was not supported by the present study, nor was the role of friendship quality as a mediator of the relation between child externalizing behavior and friendship stability. Age significantly predicted friendship stability with one very best friend and residence in a rural or urban community significantly predicted friendship stability within children's networks of 1-3 best friends. Friendship stability did not predict time 2 externalizing behavior. These results highlight the influence of child behavior, age, and contextual factors on friendship stability.

The Auroral Spatial Structures Probe (ASSP) mission is a sounding rocket mission studying solar energy input to space weather. ASSP requires the high velocity ejection (up to 50 m/s) of 6 secondary payloads, spin stabilized perpendicular to the ejection velocity. The proposed scientific instrumentation depends on a high degree of spin stability, requiring a maximum coning angle of less than 5º. It also requires that the spin axis be aligned within 25º of the local magnetic field lines. The maximum velocities of current ejection methods are typically less than 10m/s, and often produce coning angles in excess of 20º. Because of this they do not meet the ASSP mission requirements. To meet these requirements a new ejection method is being developed by NASA Wallops Flight Facility. Success of the technique in meeting coning angle and B-field alignment requirements is evaluated herein by modeling secondary payload dynamic behavior using a 6-DOF dynamic simulation employing state space integration written in MATLAB. Simulation results showed that secondary payload mass balancing is the most important factor in meeting stability requirements. Secondary mass payload properties will be measured using an inverted torsion pendulum. If moment of inertia measurement errors can be reduced to 0.5%, it is possible to achieve mean coning and B-field alignment angles of 2.16º and 2.71º, respectively.

Philosophiae Doctor - PhD / Malaria is a common infection in tropical areas, transmitted between humans through female anopheles mosquito bites as it seeks blood meal to carry out egg production. The infection forms a direct threat to the lives of many people in South Sudan. Reports show that malaria caused a large proportion of morbidity and mortality in the fledgling nation, accounting for 20% to 40% morbidity and 20% to 25% mortality, with the majority of the affected people being children and pregnant mothers. In this thesis, we construct and analyze mathematical models for malaria transmission in South Sudan context incorporating national malaria control strategic plan. In addition, we investigate important factors such as climatic conditions and population mobility that may drive malaria in South Sudan. Furthermore, we study a stochastic version of the deterministic model by introducing a white noise.

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Two major areas were studied in this research to achieve more efficient and optimised method for the prediction of ship motion, and this research has two aims. The first aim was to improve an algorithm of the oscillatory problems for strip theory by means of reducing numerical integration using the desingularised method. A new way of distributing point sources was developed by the author in order to solve the boundary problem on the source distribution. Results showed that desingularsation can be utilised on rounded hull shapes. Although the desingularsation process reduces the computational time, the conventional method is more robust and stable due to the simple source panel distribution. The second aim was an investigation of viscous roll damping of ship motion with the influence of forward velocity, and several numerical simulations were developed in order to support wind-tunnel experimentation. The wind tunnel experimentation was conducted by using a 1.2 m NACA6521 modified cylindrical-bulb model to investigate the viscous effect on the rolling motion of the ship. Since viscous damping was very small under restrictions from the experimental condition, a normal method of collecting data of roll motion, in which a device is physically attached on the bulb model, was not suitable. As a solution, remote sensing was utilised to capture the motion picture by a digital video camera. A visual analysis was then conducted to obtain data of the roll motion of the bulb model inside the wind-tunnel test section. Two different numerical simulations were developed under the hypothesis that the forward velocity influences the boundary layer generation to cause viscous roll damping on the ship model hull. The first numerical simulation uses the energy method to produce damping coefficients, and the second numerical simulation requires solving the motion of equation numerically. It was discovered that the increase of forward velocity results in a linear increase of the viscous damping coefficient. The numerical simulation and experimental data agree closely. Therefore, the theory used to predict the viscous roll damping was shown to be reasonably accurate.