Essays on applied economics

This thesis includes three empirical essays which cover different topics. Before moving to the main chapters, I would like to briefly discuss the research question and main findings of each project. Chapter 1 Black-White Wage Convergence in the United States This paper explores whether there is a pattern of heterogeneous wage convergence between black and white workers in the Southern US relative to the Non-Southern US during the post-Civil Rights era. Heterogeneity in relation to the South may be plausibly associated with a range of determinants: the region’s historical experience of slavery, different observable factors, or changing political and social institutions. My evidence from US Census data for 1980, 1990 and 2000 indicates that a strong pattern of “black-black” and “black-white” wage convergence exists between Southern born and Non-Southern born individuals. This wage convergence pattern, particularly amongst black workers, is similar across Southern states associated with different historical intensities of slavery, but it is stronger and more persistent for the low wage groups in the South. In addition, the wage convergence is mainly from the low wage quartile groups. My assessment of the impact of institutional changes as a driver of wage convergence suggests that the changes associated with rising political competition from 1960 to 1980 contributed to rising black wages. Chapter 2 Hate Crime and Victory of Obama This paper examines whether Obama’s 2008 electoral victory affected hate crimes. Hate crime data from 2005 to 2012 indicate that anti-black and total hate crimes declined significantly in Blue States after Obama won the election, relative to Red States. The drop is even more significant in States that supported the Democratic presidential candidates in the 2004 and 2008 elections. Moreover, this decline is highly associated with the decreasing education gap between black people and white people. These findings suggest that Obama’s victory played a role in reducing the number of hate crimes in the US. Chapter 3 The Long-Run Labor Market Consequences of Being Born in A Bad Economy Recent studies have shown that an economic or environmental shock at an early stage of life can have a negative long-term impact on health status as well as educational and labour market outcomes. In this study, I examine whether being born during an economic recession affects later-life earnings. By utilising 2000 US Census data, I find that males born between 1965 and 1979 experienced a 1 percent of earning loss with every one unit increase in the unemployment rate at year of birth. The effect is similar in those with and without college education. Moreover, the effect is stronger in the low wage quartile groups. These findings suggest that the labour market consequences of being born in a recession are negative and persistent

Anti-proliferation and apoptosis effects of Camellia nitidissima C. W. Chi extract on A549 lung cancer cells

Purpose: To investigate the effect of Camellia nitidissima C. W. Chi extract (CNCE) on apoptosis and proliferation in A549 human lung cancer cells.Methods: Inverted microscope was used to examine morphological changes in A549 cells after exposure to CNCE. Trypan blue staining of living cells was applied to construct the cell growth curve after treatment with varying concentrations of CNCE. The influence of CNCE on cell proliferation, apoptosis and cell cycle were determined by MTT assay. The protein expressions of key apoptosisrelated  enzymes were evaluated by immuno-cytochemical method.Results: CNCE inhibited the growth of A549 lung cancer cells at the concentration range of 20 - 160 μg/mL. Flow cytometry showed that CNCE induced apoptosis in the A549 cells. The proportion of cells in G0/G1-phase increased significantly (p < 0.01), while the proportion of cells in S-phase and G2/Mphase decreased  correspondingly, indicating that the cells were in G0/G1-phase arrest. Cell cycle arrest and apoptosis-inducing effect gradually increased with increase in CNCE concentration. With increasing concentrations of CNCE, there were significant increases in the expressions of caspase-3 (p < 0.05), caspase-8 (p < 0.01) and caspase-9 (p < 0.05), and significant decreases in Ki-67 (p < 0.01) and p21 ras protein (p < 0.01).Conclusion: CNCE exerts significant inhibitory effect on the proliferation of A549 lung cancer cells, and therefore can potentially be developed for the treatment of lung cancer.Keywords: Camellia nitidissima, Antitumor activity, Lung cancer, Apoptosis, Cell cycle arrest, Caspas

Utjecaj otopine u čvrstom stanju i starenja na mikrostrukturu i mehanička svojstva kompozita čestica SiCp/Al-Si-Cu-Mg

The SiC particles (SiCp, mass fraction 30 %) reinforced with the Al-Si-Cu-Mg matrix composite have been prepared using one-way press method, sintering, and hot extrusion. The composite was subjected to solid solution treatment at temperatures of 470 °C, 485 °C, 500 °C, 515 °C, and 530 °C for 4 h. The sample was then subjected to ageing treatment at temperatures of 160 °C and 180 °C during different times after solid solution treatment at 515 °C for 4 h. The microstructure and mechanical properties of the SiCp/Al-Si-Cu-Mg matrix composite under the different ageing and solid solution treatments were tested using SEM and TEM microhardness analysis. The results show that the white granulated metallic compounds of the SiCp/Al-Si-Cu-Mg composite materials, which are formed in the sintering process of composite materials, dissolve back after the solid solution treatment at different temperatures. The higher the solid solution temperature, the more metallic compounds dissolve back. The microhardness of the composites reached maximum after solution treatment at 515 °C for 4 h. Following the ageing treatment and with the prolongation of ageing time, the hardness of the composite material reached “double peak” phenomenon. With the increase in ageing temperature, the hardening speed of the composite material also increased, but at the same time, the hardening ability had reduced. After the ageing treatment, the second phases of the composite are discoid Al5Cu6Mg2. This work is licensed under a Creative Commons Attribution 4.0 International License.Pripravljen je kompozit čestica SiC (SiCp) u masenom udjelom 30 % u matrici Al-Si-Cu-Mg prešanjem, sinteriranjem i ekstrudiranjem. Kompozit je 4 sata bio izložen otapanju u čvrstom stanju pri 470 °C, 485 °C, 500 °C, 515 °C i 530 °C. Nakon toga na uzorak je 4 sata pri 515 °C djelovalo otapanje u čvrstom stanju, a zatim su uzorci starili različito vrijeme pri temperaturama 160 i 180 °C. Mikrostruktura i mehanička svojstva kompozita proučena su tehnikama pretražnom i transmisijskom mikroskopijom te analizom mikrotvrdoće. Pri sinteriranju kompozita SiCp/Al-Si-Cu-Mg nastaje bijeli zrnasti metalni spoj koji se otapa u čvrstu otopinu pri različitim temperaturama. Što je viša temperatura čvrste otopine, više se otopi metalnog spoja. Mikrotvrdoća doseže maksimum pri izlaganju reakcijama u čvrstom stanju pri 515 °C kroz četiri sata. Nakon starenja i s produljenjem starenja tvrdoća materijala pokazuje dvostruki vrh. S povišenjem temperature povećava se brzina očvršćivanja, no istodobno se smanjuje mogućnost očvršćenja. Druga faza kompozita nakon starenja je diskoidni Al5Cu6Mg2. Ovo djelo je dano na korištenje pod licencom Creative Commons Imenovanje 4.0 međunarodna