Ph. D.

Ph.D.

This research was designed to investigate attitudes toward and perceptions of divorce; more specifically, the investigator analyzed the data by total scores and four sub-scale scores measuring 1. General attitudes toward divorce as an institution. 2. Attitudes toward people who are divorced. 3. Perceptions of the effects of divorce on children. 4. Perceptions of one's friendship role in a divorce situation. Two-hundred and eleven usable four page anonymous questionnaires, developed by the investigator, were completed by single undergraduate students attending the Virginia Polytechnic Institute, Blacksburg, Virginia, during the Spring quarter, 1969. The total scores and the four sub- scale scores were analyzed by sex, socio-economic status, residence, and exposure to divorce. Females were found to be more liberal in their perceptions of the effects of divorce on children at the .02 level of confidence. Respondents with exposure to divorce were found to be significantly more liberal at the .05 level of confidence in their attitudes toward divorce as an institution. The largest percentage of respondents perceived the major causes of divorce to be first - sexual adjustment, second - nagging husband or wife, and third - money matters in the form of managing the money or being successful in an occupation. More males perceived the consequences of divorce to be relief and happiness; more females perceived the consequences of divorce to be guilt and unhappiness. Fifty-seven per cent of the respondents stated they would feel uncomfortable marrying a divorcee themselves. / Master of Science

This study is concerned with the use of "Flying squads" in municipal fire departments. Specifically, the research effort involves development of a mathematical model and solution procedure for the optimum use of flying squads as manpower transport vehicles. The exact problem considered in this thesis is that of determining (a) the number of flying squads to use, (b) the locations/allocations of each flying squad, (c) the deployment strategy of each squad, and (d) the size of each squad and the job skill levels of each member of the squads. In formulating the model, the opinions of professionals in the field, as gathered through a written survey, were utilized to develop the appropriate constraints and objective function. The objective function minimizes an estimate of the cost to society which includes the estimated fire losses and the cost of operating flying squads. The model involves constraints associated with (a) the maximum response time, (b) the potential demand for fire services, (c) the workload of a flying squad, and (d) the maximum number of squads to have. The mathematical model developed is a mixed integer programming problem having a similar structure to the Capacitated Warehouse Location Problem. A Branch and Bound type algorithm based on previous work by Akinc and Khumawala is developed to solve the problem. An example of this problem as it actually exists in the Roanoke Virginia Fire Department is modeled and solved. The results obtained from this study demonstrates that flying squads have a potential use as an alternative method of manning the companies in municipal fire departments. / Master of Science

In the manufacture of cellulose nitrate plastic some physical damage of the finished product always results during drying. The drying conditions should be studied and improved. The purpose of this investigation was to determine the effects of relative water humidity, convection heat and radiant heat on the drying of cellulose nitrate plastic. The conditions causing case-hardening and physical damage were observed, drying rate was determined and drying time compared. Specimens of cellulose nitrate plastic sheet, plasticized with camphor, were soaked in 95 percent ethyl alcohol. They were first dried in a compartment dryer by conditioned air, with or without radiant heat. Then, they were removed to a zero relative humidity desiccator to be dried until the weight became constant within a one-day period. The values of relative humidity studied were 30, 40, 50 and 60 percent. The air temperatures studied were 110, 120, 130 and 140 °F. The detailed data were not obtained at 60 percent relative humidity and at 140 °F because these conditions could not be controlled. The radiant heat was supplied from two electric hot plates and used to increase the internal temperature of the plastic. The effect of increasing the relative humidity was to reduce or avoid damage to the plastic and to reduce the drying rate at higher alcohol content. This effect increased with the increase of air temperature and became less as the alcohol content decreased. It disappeared at 0.225 gram alcohol per gram dry weight as dried at 110 °F and temperature, and at 0.17 gram per gram dry weight as dried at 130 °F. Increasing the air temperature increased the drying rate and shortened the drying time. The maximum safe air temperature for drying cellulose nitrate plastic without radiant heat was between 130 and 140 °F, physical damage occurring at 140 °F. Radiant heat could be applied to raise the internal temperature of the wet plastic and to increase the drying rate without causing case-hardening, the effect being slightly greater with a thick plastic of darker color than with a thin plastic of light color. When the internal temperature of the wet plastic was raised to 128 and 130 °F by supplementary radiant heat, with drying air of 110 °F and 50 and 30 percent relative humidity, respectively, the drying rate was increased, but physical damage to the plastic resulted. / Master of Science

Vertical greenery systems (VGSs) on building walls in cities develop rapidly worldwide in recent years, which is a potentially effective way to mitigate urban heat island (UHI) effect mainly through evapotranspiration and shading. Benefits of using vertical greening applications are of social and environmental origins, such as CO₂ emission reduction, energy saving, air quality improvements and enhanced aesthetic. However, little is known about C sequestration and CO₂ flux of vertical greening, and less attention has been paid on the C balance of vertical greening. In addition, many factors have great influence on C sequestration of vertical greening, including plant species, orientations and fertilizer application. However, limited studies report their impacts on C cycling, mitigation of UHI effect and improvement of urban microclimate of vertical greening. / Firstly, C sequestration of seven common plant species and that of Peperomia claviformis under six fertilizer treatments were studied. The results showed that plant species and fertilizer application had significant effects on shoot and root biomass. In contrast, we investigated C sequestration of Schefflera octophylla in four orientations, and showed that orientation had no significant influence. C sequestration of the seven species in VGSs ranged from 61 to 523 g C m⁻² y⁻¹. Meanwhile, the total C footprint of their maintenance ranged from 196 to 434 g Ce m⁻² y⁻¹, including the C footprint of fertilizer, pesticide and electricity consumption for irrigation. Newly established VGSs with these seven species could become C source from C sinks with large amount of C emissions from the maintenance practices between 2.7 and 43.6 years. / Secondly, the CO₂ fluxes of VGSs were determined by chamber-based measurement. Plant species and photosynthetically active radiation (PAR) played a dominant role in CO₂ fluxes. Fertilizer also significantly contributed to CO₂ fluxes of VGSs. Net ecosystem exchange (NEE) of CO₂ and respiration rates of VGSs varied with plant species, and most species in VGSs were higher in summer than other seasons. / Thirdly, VGS in the west-facing wall had the best capacity in terms of daily maximum wall temperature on sunny days. In addition, VGSs decreased the indoor air temperature of the thermal test room with VGSs. Solar radiation, total bright sunshine and relative humidity had the greatest significant correlations and relatively stronger coefficients with thermal indicators. / Finally, we compared the electricity consumption for cooling in flats with and without a VGS (8.22m²) in a pubic housing estate, and quantified the environmental benefits and burdens of a commercially available VGS. The daily electricity saving by the VGS in the flats with and without a VGS (8.22m²) in sunny, cloudy and rainy days in summer was 1.30, 0.84 and 0.71 kWh, respectively. A life cycle assessment (LCA) was conducted to analyze the environmental burdens of the VGS in its material, transportation, use and end-of-life stages. A comparison of the environmental burdens and benefits gained from cooling showed that the environmental burden of the VGS in regard to abiotic depletion of fossil fuels could be paid back in 20 years. / Overall, vertical greeneries installed on building walls did not only play a significant role on alleviation the problems of global warming and climate change through C sequestration and energy saving, but alse contribute to mitigating the UHI effects and improving urban microclimate due to the thermal performance. / 近年來城市中垂直綠化快速發展，主要通過植物蒸騰和遮陰效應而成為一種減緩城市熱島效應的有途徑。垂直綠化的應用由於其多種社會和環境效益，比如降低二氧化碳排放、節能、提高空氣品質和提升審美效果。然而，我们對於垂直绿化的碳匯和二氧化碳通量所知甚少，并且很少有研究關注垂直绿化的碳收支。並且，許多因素影響垂直綠化的碳匯，包括植物品種、朝向和施肥。但是在垂直綠化的碳循環、減緩城市熱島效應和提升城市微氣候方面研究卻很少。 / 首先，我们研究了七種常见的垂直绿化植物的碳汇和黑叶椒草在六种不同施肥处理下的碳匯。结果显示，植物品種和施肥對茎部和根部生物量有顯著促進作用。相比之下，我們還研究了鵝掌柴在四個朝向的碳匯，結果顯示，朝向對其並沒有顯著影響。七種垂直綠化植物的碳匯範圍為每年每平方米61到253克碳。同時，這些植物的維護包括施肥、噴藥和灌溉用電，造成了每年每平方米196到434克碳排放。因此，由於維護所造成的大量碳排放。所以這七種植物垂直綠化系統在2.7年到43.6年之內將從碳源變成碳匯。 / 第二，我們用二氧化碳分析儀測定了垂直綠化的碳通量。植物品種和光合有效輻射在碳通量上起主導作用。施肥也同樣顯著影響垂直綠化的碳通量。淨生態系統碳交換量和呼吸速率隨植物品種而變化，並且在夏天高於其他季節。 / 第三，在晴天最大牆面溫度上，西向的垂直綠化有佳的植物降效應。並且，垂直綠化降低了測試房間的室內空氣溫度。太陽輻射、總日照和相對濕與熱能指標有最多的顯著關係，並且有更高的相關係數。 / 最後，我們比較了在公共住宅的有垂直綠化(8.22平方米)和無垂直綠化的房間用於降溫的電量消耗，並評估了一個商業化垂直綠化系統的環境效益和環境負荷。在對比已安裝和未安裝垂直綠化的兩個房間後，在晴天、陰天和雨天每日省電量分別為1.30, 0.84 and 0.71千瓦時。我們用生命週期評價來對垂直綠化在材料、運輸、使用和最終階段的環境負荷進行了分析。對比了垂直綠化的環境效益和環境負荷後可知，化石燃料的不可再生資源消耗能夠在20年內償還。 / 總之，建築物外牆的垂直綠化不僅通过其碳匯和节能作用能夠對溫室效應和氣候變化有顯著作用，而且由于其熱性能還能緩解城市熱島效應和提升微氣候。 / Pan, Lan. / Thesis Ph.D. Chinese University of Hong Kong 2016. / Includes bibliographical references (leaves 217-246). / Abstracts also in Chinese. / Title from PDF title page (viewed on 24, October, 2016). / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only.

Twenty two methionine-containing di- to octa-peptides were evaluated for their ability to serve as methionine sources to support protein accretion and cell proliferation in C₂C₁₂ myogenic, MAC-T mammary epithelial and ovine myogenic satellite cells. Factors in serum that may be involved in regulating peptide utilization was investigated using MAC-T cells. Growth of MAC-T cells was studied in the presence of methionine-containing dipeptides with 6% desalted adult animal serum from chickens, horses, humans, pigs or rabbits. Serumal peptidase activities on the twenty two methionine-containing peptides were examined in cell-free, methionine-free Dulbecco’s modified Eagle’s medium supplemented with 6% fetal bovine serum. The cell cultures were incubated for 72 h at 37°C in a humidified environment of 90% air : 10% CO₂ for C₂C₁₂ and ovine satellite cells or 95% air : 5% CO₂ for MAC-T cells. The basal medium contained methionine-free Dulbecco’s modified Eagle’s medium supplemented with 6% desalted animal serum or one of the following serumal factors: .4% bovine serum lipids, 1% chemically defined lipid concentrate, bovine insulin (1 ug/mL), or 3% low protein serum replacement (LPSR-1). Treatment media tested included basal medium or basal media supplemented with L-methionine or one of the methionine-containing peptides. Cell cultures incubated with the basal media for 72 h were characterized by decreased cell number and decreased protein content compared with initial cultures. All the methionine-containing peptides (with the exception of glycylmethionine and prolylmethionine for C₂C₁₂ cells), regardles of chain length, were able to support protein accretion with responses ranging from 29 to 123% of that of free L-methionine. The DNA contents of ovine satellite cell cultures indicated that cell proliferation occurred in the presence of all the methionine-containing peptides with responses ranging from 45 to 144% of the L-methionine response. Bovine insulin and lipids were not effective in promoting peptide utilization by MAC-T cells. However, the LPSR-1 facilitated the utilization of methionine-containing peptides in C₂C₁₂ and MAC-T cells. In the cell-free, methionine-free Dulbecco’s modified Eagle’s medium, peptidases could release all the methionine residues from the tetra- to octapeptides during 24 h of incubation and 42 to 70% of the methionine residues from the di- and tripeptides tested. The results demonstrated that cultured animal cells possess the ability to utilize methionine-containing peptides as methionine sources for protein accretion and cell proliferation, but serumal peptidases are at least partially responsible for the observed responses. / Ph. D.

A series of wind tunnel tests were conducted to determine the aerodynamic forces and moments produced by several clamped oblique wings. The wing sweep and aileron deflection angles were varied throughout a wide range of dynamic pressures. The wing structure was also stiffened. Strains were measured in the swept forward wing panels. Results from these tests showed that increasing the wing structural stiffness or applying aileron deflection would increase the wing divergence speed. The divergence speed decreased as the sweep angle increased. Further tests were conducted with the wing unconstrained in roll. Results showed that an oblique wing will attempt to unload its sweptforward panel by assuming a banked position. The wings were found to flutter before unclamped divergence occurred. Finally, it was found that the wing loading of an oblique wing can remain constant for a given aileron deflection throughout a wide range of velocities including velocities above the clamped divergence speed. / Master of Science

Lors de mes travaux de thèse je me suis intéressée à l’invasion des hépatocytes par Plasmodium. Bien que certains récepteurs cellulaires mis en jeu aient déjà été identifiés tels que CD81 et SR-B1, les facteurs parasitaires restaient à identifier. J’ai testé différents facteurs parasitaires grâce à un protocole de test d’invasion de cellules HepG2 et HepG2/CD81 par des parasites complémentés avec différentes protéines. Suite à l’identification de la protéine P36 comme déterminant du choix de la voie d’entrée dans les hépatocytes, j’ai étudié les déterminants structuraux de cette protéine nécessaires à la détermination de la voie d’entrée. Pour cela j’ai complémenté des parasites délétés pour P36 avec des protéines chimériques exprimant les domaines d’un parasite utilisant à la fois les récepteurs CD81 et SR-B1 et des domaines d’un parasites ne pouvant utiliser que la voie CD81. J’ai identifié le second domaine à 6 cystéine de P36 comme déterminant du choix de la voie d’invasion. Afin d’étudier les interactions de P36 avec d’éventuels récepteurs cellulaires, j’ai produit cette protéine en système bactérien. Les protéines ont été utilisées pour réaliser des tests d’interactions (ELISA et SPR) avec des récepteurs d’intérêt : CD81, SR-B1, CD36, LIMPII et EphA2 qui n’ont malheureusement pas permis d’identifier le ligand de P36. Des anticorps sont également en cours de production, dans le but d’une part de tester s’ils sont capables de bloquer l’invasion des hépatocytes par Plasmodium et d’autre part de localiser la protéine chez le parasite. Enfin, j’ai étudié les polymorphismes des protéines P36 de parasites infectant l’homme. / During my thesis, I was interested in the study of the hepatocyte invasion by Plasmodium. Several cellular receptors are involved, such as CD81 and SRB1, but the parasitic factors required were unknown until now. I tested different parasitic factors thanks to an invasion test of HepG2 or HepG2/CD81 cells with parasites complemented with different proteins. Following the identification of the 6 cystein protein P36 as a determinants of the entry pathway, I studied the structural determinants of this protein which are involved in the hepatocytes’ entry pathway. To this end, I complemented parasites knock-out for P36 with chimeric proteins constituted of domains of a parasite using both CD81 and SRB1, and domains from a parasite using only CD81. I showed that the second 6 cystein domain of P36 is decisive in the entry pathway choice.In order to study the P36 interactions with potential cellular receptors, I developed a production protocol of this protein in bacteria. I used the recombinant protein to test the interactions (ELISA and SPR) with potential receptors: CD81, SRB1, CD36, LIMP2, Epha2. Unfortunately, no interaction has been detected. Antibodies are in production, in order to test whether they are capable to block the hepatocyte invasion by Plasmodium. They will also be used to localize the protein in the parasite. In the end, I studied the polymorphisms of P36 in human parasites.

Martin Ravallion ("Why Don't We See Poverty Convergence?" American Economic Review, 102(1): 504-23; 2012) presents evidence against the existence of convergence in global poverty rates despite convergence in household mean income levels and the close linkage between income growth and poverty reduction. We show that this finding is driven by a specification that demands more than simple convergence in poverty headcount rates and assumes a growth elasticity of poverty reduction, which is well-known to accelerate with low initial poverty levels. If we motivate the poverty convergence equation using an arguably superior growth semi-elasticity of poverty reduction, we find highly significant and robust evidence of convergence in absolute poverty headcount ratios and poverty gaps. Relatedly, we show that the results in Ravallion (2012) are driven by the special income growth and poverty dynamics in Central and Eastern European transition economies that started with low initial poverty rates and thus observed a high elasticity of poverty reduction. Once we control for their abnormal poverty dynamics, we again find robust evidence of global convergence in poverty, even in the original specification by Ravallion (2012). (authors' abstract) / Series: Department of Economics Working Paper Series