Essays on Economics of the Family

In the first chapter, I explore the role of gender discrimination in children’s investments by parents. I specifically examine whether parents in urban China devote more household resources, specifically education, health, and total expenditures, to girls than to boys. The empirical literature has extensively examined trends in the sex ratio at birth and the effect of gender on the extensive margin of fertility. Much less of the existing literature has explored the impact of gender on the intensive margin of parental inputs mainly because of lack of individual child-level data, especially in urban China. This is an important area for economic research to help disentangle child gender bias and provide insight on the well-being of Chinese children. To answer my research question, I use unique data, Chinese Child Twin Survey (CCTS) that includes family expenditure information for individual children within the family. Estimating the causal effect of child gender on parental investments requires boys and girls to live in families with similar observable and unobservable characteristics. This assumption may be violated in China for two reasons. First, some families use ultrasound technology to engage in sex selection at birth, which may indicate that parents who have boys are different from those who have girls. Second, if families have a preference for sons and parents base fertility decisions on the gender of previous children, girls will end up in larger families on average. Since larger families have fewer resources per capita, this implies that girls on average will be allocated fewer resources. To address the empirical challenges, I leverage the randomness of the first child’s gender and utilize a twin-fixed effect estimator. My results suggest that average yearly educational expenditures are 18 percentage (48.9 U.S. dollars in 2020 value) higher for first-born girls than for first-born boys in households with firstborn singletons. For households with first-born twins, compared to a male twin sibling, the female iitwin sibling received 25 percentage (59.8 U.S. dollars) more in yearly educational expenditures. To further provide insight on how parents allocate resources across their children within the framework of economic theory, I adopt a collective-household model to structurally estimate the total spending on each twin sibling to account for the resource sharing among twins. Consistent with the results of the twin-fixed-effects model, my estimates show that parents allocate more household resources to girls. The second chapter of this dissertation, which is joint work with Scott Barkowski and Joanne Song McLaughlin, examines the effect of young children on the labor supply of parents during COVID-19. Using the monthly Current Population Survey (CPS), and following a preanalysis plan, we implement three variations of an event study research design comparing workers with childcare responsibilities to those without. The first compares parents with young children (under age 13) who have childcare needs to those without young children. For a sample limited to parents of young children, the second and third rely on the presence of someone who could provide childcare in the household: a teenager in one and a grandparent in the other (as control groups). We analyze three outcomes: whether parents were “at work” (not sick, on vacation, or otherwise away from his or her job); whether they were employed; and hours worked conditional being employed. Contrary to our expectation, we find the labor supply of parents with young children was not negatively affected during the pandemic. Instead, some evidence suggests they were more likely to be working after the pandemic unfolded. For the outcomes of being at work and employed, our results are not systematically different for men and women. However, some findings suggest women with young children worked almost an hour longer per week than those without. We provide evidence from questions newly added to the CPS during the pandemic that parents were more likely to work remotely than non-parents, suggesting employer flexibility with regard to telework aided parents in avoiding negative shocks to their labor supply

Young Children and Parents' Labor Supply during COVID-19

We study the COVID-19 pandemic’s effects on the labor supply of parents with young children. Using the monthly Current Population Survey, and following a pre-analysis plan, we use three variations of difference-in-differences to compare workers with childcare needs to those without. The first compares parents with young children and those without young children, while the second and third rely on the presence of someone who could provide childcare in the household: a teenager in one and a grandparent in the other. We analyze three outcomes: whether parents were “at work” (not sick, on vacation, or otherwise away from his or her job); whether they were employed; and hours worked. Contrary to expectation, we find the labor supply of parents with young children was not negatively affected by the COVID-19 pandemic. Instead, some evidence suggests they were more likely to be working after the pandemic unfolded. For the outcomes of being at work and employed, our results are not systematically different for men and women, but some findings suggest women with young children worked almost an hour longer per week than those without. These results suggest that factors like employers allowing employees to work at home and informal sources of childcare aided parents in avoiding negative shocks to their labor supply during the pandemic

Young Children and Parents' Labor Supply during COVID-19

We study the COVID-19 pandemic’s effects on the labor supply of parents with young children. Using the monthly Current Population Survey, and following a pre-analysis plan, we use three variations of difference-in-differences to compare workers with childcare needs to those without. The first compares parents with young children and those without young children, while the second and third rely on the presence of someone who could provide childcare in the household: a teenager in one and a grandparent in the other. We analyze three outcomes: whether parents were “at work” (not sick, on vacation, or otherwise away from his or her job); whether they were employed; and hours worked. Contrary to expectation, we find the labor supply of parents with young children was not negatively affected by the COVID-19 pandemic. Instead, some evidence suggests they were more likely to be working after the pandemic unfolded. For the outcomes of being at work and employed, our results are not systematically different for men and women, but some findings suggest women with young children worked almost an hour longer per week than those without. These results suggest that factors like employers allowing employees to work at home and informal sources of childcare aided parents in avoiding negative shocks to their labor supply during the pandemic

Effect of fluid pressure gradient on the factor of safety in rock stability analysis

Inappropriate assessment of rock stability may result in anthropogenic geohazards during underground space development and energy extraction. To reasonably estimate the factor of safety (FOS) for rock stability, it is critical to address uncertainties involved in the estimation. Fluid pressure gradient is of great concern in the estimation of the FOS. We carried out laboratory experiment and numerical modeling to reproduce fluid pressure gradient on a smooth fracture in granite. We compared the FOS derived from a nearly uniform fluid pressure gradient and that from a significantly non-linear fluid pressure gradient and found that the non-linear gradient of fluid pressure may amplify the FOS value. We also conducted a theoretical analysis to compare the FOS values for uniform, linear, and non-linear fluid pressure gradients. The results revealed that a considerable gradient and a pronounced non-linearity of fluid pressure are likely to cause premature failure of a rock fracture. Moreover, the upper bound of the FOS with a non-linear fluid pressure gradient depends on the initial FOS for a rock fracture without fluid pressurization. These findings are conducive to interpreting rock instability due to fluid pressurization and developing a more robust FOS estimation method.Ministry of Education (MOE)This study was supported by Ministry of Education, Singapore, under Grant No. RG152/19

Detection of ADAMTS‑4 Activity Using a Fluorogenic Peptide-Conjugated Au Nanoparticle Probe in Human Knee Synovial Fluid

A disintegrin and metalloproteinase with thrombospondin motif-4 (ADAMTS-4) plays a pivotal role in degrading aggrecan, which is an early event in cartilage degrading joint diseases such as osteoarthritis (OA). Detection of ADAMTS-4 activity could provide useful clinical information for early diagnosis of such diseases and disease-modifying therapy. Therefore, we developed a ADAMTS-4 detective fluorescent turn-on AuNP probe (ADAMTS-4-D-Au probe) by conjugating gold nanoparticles with a FITC-modified ADAMTS-4-specific peptide (DVQEFRGVTAVIR). When the ADAMTS-4-D-Au probe was incubated with ADAMTS-4, the fluorescence recovered and fluorescence intensity markedly increased in proportion to concentrations of ADAMTS-4 and the probe. A nearly 3-fold increase in fluorescent intensity in response to only 3.9 pM of ADAMTS-4 was detected, whereas almost no fluorescence recovery was observed when the probe was incubated with matrix metalloproteinase (MMP)-1, -3, and -13. These results indicate a relative high sensitivity and specificity of the probe. Moreover, ADAMTS-4-D-Au probe was used to detect ADAMTS-4 activity in synovial fluid from 11 knee surgery patients. A substantial increase in fluorescent intensity was observed in the acute joint injury group as compared to the chronic joint injury and end-stage OA groups, indicating that this simple and low-cost sensing system might serve as a new detection method for ADAMTS-4 activity in biological samples and in screens for inhibitors for ADAMTS-4-related joint diseases. Additionally, this probe could be a potential biomarker for early diagnosis of cartilage-degrading joint diseases