Essays on firms, technology, and macroeconomics

This thesis consists of three chapters. Chapter 1 studies the role of marketing in the economy. Using aggregate and firm-level data, I find that aggregate marketing intensity in the US increased sharply around the mid-1990s, which coincides with a rapid rise of elasticity between firm-level Marketing Production Cost Ratio and markup. To explain these facts, I develop a model with heterogeneous firms and endogenous markups in which firms engage in marketing to signal their quality. I use a calibrated version of the model to quantify the impact of information frictions and marketing on aggregate productivity. I find that quality information revealed by marketing is valuable and access to marketing cannot undo the information frictions completely. Chapter 2 examines the impact of zombie firms on resource allocation. Using firm-level data in China, I show that zombie firms are larger, less productive, and receive a higher subsidy rate on average. The difference in average subsidy rate between zombies and non-zombies reflects both the selection criterion of zombies and the underlying joint distribution of subsidy rate and productivity. I develop a model with heterogeneous firms to quantify the impact of zombies on aggregate productivity. Quantitative exercise shows that reducing the dispersion in subsidy rate across firms can lead to significant productivity gains, while policies that increase the exit rate of zombies have limited productivity effects. Chapter 3 establishes two facts along with the rise of information technology: (i) the output from the information sector is more intensively used as an intermediate input; (ii) the wage of information workers and their total employment increase relative to those of non-information workers. To understand the causes, we develop a two-sector accounting framework with sector-factor specific technical changes. We find that labor-augmenting technical change is important in explaining the observed change in wage premium and intermediate shares

Non-Ischemic, Non-Hypoxic Myocardial Injury, and Long-Term Mortality in Patients with Coronavirus Disease 2019: A Retrospective Cohort Study.

Cardiac damage is commonly reported in patients with coronavirus disease 2019 (COVID-19) but its prevalence and impact on the long-term survival of patients remain uncertain. This study aimed to explore the prevalence of myocardial injury and assess its prognostic value in patients with COVID-19. A single-center, retrospective cohort study was performed at the Affiliated Hospital of Jianghan University. Data from 766 patients with confirmed COVID-19 who were hospitalized from December 27, 2019 to April 25, 2020 were collected. Demographic, clinical, laboratory, electrocardiogram, treatment data and all-cause mortality during follow-up were collected and analyzed. Of the 766 patients with moderate to critically ill COVID-19, 86 (11.2%) died after a mean follow-up of 72.8 days. Myocardial injury occurred in 94 (12.3%) patients. The mortality rate was 64.9% (61/94) and 3.7% (25/672) in patients with and without myocardial injury, respectively. Cox regression showed that myocardial injury was an independent risk factor for mortality (hazard ratio: 8.76, 95% confidence interval: 4.76-16.11,    0.001). Of the 90 patients with myocardial injury with electrocardiogram results, sinus tachycardia was present in 29, bundle branch block in 26, low voltage in 10, and abnormal T-wave in 53. COVID-19 not only involves pneumonia but also cardiac damage. Myocardial injury is a common complication and an independent risk factor for mortality in COVID-19 patients

Hybrid Arch Repair with Supra-Aortic Debranching and Using Castor Stent-Graft

Background The management of aortic lesions involving the aortic arch in patients who cannot tolerate thoracotomy is a challenge. Case Description A 32-year-old woman who underwent a giant aneurysm at the proximal end of the descending aorta with significant vascular wall calcification. The patient underwent Castor single-branched stent-grafting in the brachiocephalic trunk combined with surgical supra-aortic debranching, which avoided surgical aortic arch replacement and stent fenestration.reopening. The patient was followed up for 9 months, and surgery-related complications were not observed. Conclusion Hybrid arch repair with supra-aortic debranching and using Castor single-branched stent can be used to treat aortic lesions involving the aortic arch

Extending the Behavioral Geography within the Context of Forest Restoration: Research on the Geographical Behaviors of Northern-Migrating Asian Elephants (<i>Elephas maximus</i>) in Southwest China

In 2021, the northward migration of Asian elephants in southwestern China’s Yunnan Province attracted significant public attention. Exploring the behavior of Asian elephants will help to better protect this endangered species and further realize the harmonious coexistence of humans and elephants. Based on the news texts regarding the northward migration of Asian elephants, this study used network text analysis, social network analysis, and grounded theoretical research methods to explore the behavioral characteristics and internal motivations of Asian elephants during their northward migration. The results indicate that: (1) during the northward migration of Asian elephants, moving and foraging are their most frequent behaviors, and foraging may be the chief purpose of the migration. (2) Different behaviors of Asian elephants hide their behavioral choice preferences, including environmental, time, and behavioral preferences. During the migration, Asian elephants mostly move in low-altitude areas, often foraging or migrating around farmland in the afternoon or at night, returning to the mountains to rest in the early morning. Corn, rice, and other crops are their primary food; the change in their eating habits is influenced by the lack of herbs and woody plants inside the protected area. (3) The northward migration behavior of elephant herds is influenced by various factors, such as elephant population expansion, habitat change, and species migration characteristics, and the relationship between conservation and development needs to be balanced

Molecular Cloning, Bioinformatic Analysis, and Expression of Bombyx mori Lebocin 5 Gene Related to Beauveria bassiana Infection

A full-length cDNA of lebocin 5 (BmLeb5) was first cloned from silkworm, Bombyx mori, by rapid amplification of cDNA ends. The BmLeb5 gene is 808 bp in length and the open reading frame encodes a 179-amino acid hydroxyproline-rich peptide. Bioinformatic analysis results showed that BmLeb5 owns an O-glycosylation site and four RXXR motifs as other lebocins. Sequence similarity and phylogenic analysis results indicated that lebocins form a multiple gene family in silkworm as cecropins. Quantitative real-time PCR analysis revealed that BmLeb5 was highest expressed in the fat body. In the silkworm larvae infected by Beauveria bassiana, the expression level of BmLeb5 was upregulated in the fat body and hemolymph which are the most important immune tissues in silkworm. The recombinant protein of BmLeb5 was for the first time successfully expressed with prokaryotic expression system and purified. There are no reports so far that the expression of lebocins could be induced by entomopathogenic fungus. Our study suggested that BmLeb5 might play an important role in the immune response of silkworm to defend B. bassiana infection. The results also provided helpful information for further studying the lebocin family functioned in antifungal immune response in the silkworm

Cohort Profile: The Xiamen Pubertal Growth Cohort Longitudinal Study

This cohort was set up to capture pubertal onset among children in China and to analyze how timing of pubertal onset would influence cardiovascular disease risk in later life. Pubertal onset was defined as secondary sexual characteristics (SSC) attained Tanner II stage, which was breast development for girls and testis of 4 mL for boys. Meanwhile, height growth spurt, defined as age of take-off and age of peak height velocity, were also involved to observe the consistency between the three indicators in discriminating pubertal onset. The study was conducted in Xiamen, China from November 2017 to November 2020 with 6-month gaps. One thousand, four hundred and sixteen children from four project schools who had not yet started puberty were involved at baseline. By November 2020, 1272 children were still under follow-up, with 945 (74.3%) of them reaching Tanner II stage. We would continue to follow the pubertal development, as well as change in crucial risk factors for cardiovascular disease in these participants. Evidence from the present cohort study would help to reveal the influence of pubertal growth on long-term cardiovascular health and would be one of the very first studies to provide such evidence from Asian countries

Association between pubertal development and elevated blood pressure in children

Abstract Blood pressure (BP) increased with age and height development, but little was known about the effect of pubertal development on blood pressure in children. A cross‐sectional study was performed among 4146 children aged 7–12 years old in China. Pubertal development was assessed based on breast stages and testicular volume. The associations of pubertal development with BP levels and the rate of elevated blood pressure (EBP) were quantified using multiple linear and logistic regressions. We found that pubertal developmental level was positively correlated with BP, and children who experienced puberty onset and early pubertal timing had higher BP levels and prevalence of EBP. After adjusting for covariates, children experienced puberty onset had 3.84 and 2.24 mmHg increase in systolic blood pressure and diastolic blood pressure, and 70%, 53%, and 62% increased odds of EBP, ESBP, and EDBP, respectively, compared with those without puberty onset. Similar results were observed for children who had early pubertal timing. The change of BP in puberty is greater and the association between pubertal development and BP is stronger in girls than boys. These findings suggested that pubertal development could be an important independent factor and one critical period for the EBP progress. Monitoring and management of pubertal development are necessary particularly among girls

Caspase-1-Dependent Pyroptosis of Peripheral Blood Mononuclear Cells Is Associated with the Severity and Mortality of Septic Patients

Purpose. Pyroptosis has been known to play a vital role in the inflammation process which was induced by infection, injury, or inflammatory disease. The present study was aimed at evaluating the percentage of peripheral blood mononuclear cell (PBMC) pyroptosis in septic patients and assessing the correlation of PBMC pyroptosis with the severity and the mortality of septic patients. Methods. 128 trauma-induced patients with sepsis were enrolled in this prospective cohort study. Blood samples were collected, and PBMC pyroptosis was measured by flow cytometry within 24 hours after sepsis was diagnosed. Results. Percentage of PBMC pyroptosis was positively correlated with the acute physiology and chronic health evaluation (APACHE) II score and sequential organ failure assessment (SOFA) score (all P14.17%) and increased risk of the 28-day mortality (hazard ratio=1.234, 95% CI, 1.014–1.502). Conclusion. The percentage of PBMC pyroptosis increases in septic patients, and the increased percentage of PBMC pyroptosis is associated with the severity of sepsis and the 28-day mortality of patients with sepsis