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- All Subjects: development
- All Subjects: blow flies
- Creators: Weidner, Lauren
- Status: Published
The first chapter is motivated by the fact that a prominent feature of cities in developing countries is the existence of slums: locations with low housing-quality and informal property rights. This paper focuses on the allocation of land across slums and formal housing, and emphasizes the role of living in central urban areas for the formation of slums. I build a quantitative spatial general equilibrium model to study the aggregate effects of anti-slum policies and use microdata from India for the quantitative implementation. According to my findings, demolishing slums in central urban areas leads to a decrease in welfare, aggregate labor productivity, and urban population. In contrast, decreasing formal housing distortions in India to the U.S. level increases the urban population share by 20% and labor productivity by 2.4%, and reduces the share of the urban population living in slums by 19%.
The second chapter is motivated by the fact that labor productivity gaps between rich and poor countries are much larger for agriculture than for non-agriculture. Using detailed data from Mexican farms, this paper shows that value added per worker is frequently over two times larger in cash crops than in staple crops, yet most farmers choose to produce staples. These findings imply that the agricultural productivity gap is actually a staple productivity gap and understanding production decisions of farmers is crucial to explain why labor productivity is so low in poor countries. This paper develops a general equilibrium framework in which subsistence consumption and interregional trade costs determine the efficient selection of farmers into types of crops. The quantitative results of the model imply that decreasing trade costs in Mexico to the U.S. level reduces the ratio of employment in staple to cash crops by 17% and increases agricultural labor productivity by 14%.
The first chapter studies the aggregate consequences of misallocation in a firm dynamics model with multi-establishment firms. I calibrate my model to the US firm size distribution with respect to both the number of employees and the number of establishments, and use it to study distortions that are correlated with establishment size, or so-called size-dependent distortions to establishments, which are modeled as implicit output taxes. In contrast to previous studies, I find that size-dependent distortions are not more damaging to aggregate productivity and output than size-independent distortions, while the implicit tax revenue approximately summarizes the effects on aggregate output. I also use the model to compare the effects of size-dependent distortions to establishments and to firms, and find that they have different effects on firm size distribution, but have similar effects on aggregate output.
The second chapter studies the effects of product market frictions on firm size distribution and their implications for industrial pollution in China. Using a unique micro-level manufacturing census, I find that larger firms generate and emit less pollutants per unit of production. I also provide evidence suggesting the existence of size-dependent product market frictions that disproportionately affect larger firms. Using a model with firms heterogeneous in productivity and an endogenous choice of pollution treatment technology, I show that these frictions result in lower adoption rate of clean technology, higher pollution and lower aggregate output. I use the model to evaluate policies that eliminate size-dependent frictions, and those that increase environmental regulation. Quantitative results show that eliminating size-dependent frictions increases output by 30%. Meanwhile, the fraction of firms using clean technology increases by 27% and aggregate pollution decreases by 20%. In contrast, a regulatory policy which increases the clean technology adoption rate by the same 27%, has no effect on aggregate output and leads to only 10% reduction in aggregate pollution.
The subcategory of evidence deemed trace evidence is frequently seen in crime scenes, and while it is commonly the smallest evidence around, that doesn’t stop it from greatly contributing to the findings at the scene. Blood evidence may be categorized into this group in certain cases at crime scenes, especially in cases of transfer between two objects or people. In this study, the transfer of blood across both porous and non-porous substrates was examined to determine the persistence of blood across both substrates. The resulting stains after each trial of transfers were tested with a presumptive blood test commonly used in crime labs, the Kastle-Meyer test. Throughout all trials of the experiment, it was determined that blood on a non-porous surface typically dries faster as long as there isn’t a pooling effect, which hinders the ability for a stain to be continuously transferred and detected by Kastle-Meyer. Conversely, porous substrates are more likely to absorb and retain the blood in the material, allowing the blood to be released when pressure is applied, causing the stain to transfer more easily and result in a stain that will produce a positive Kastle-Meyer result.
Medicolegal forensic entomology is the study of insects to aid with legal investigations (Gemmellaro, 2017). Insect evidence can be used to provide information such as the post-mortem interval (PMI). Blow flies are especially useful as these insects are primary colonizers, quickly arriving at a corpse (Malainey & Anderson, 2020). The age of blow flies found at a scene is used to calculate the PMI. Blow fly age can be estimated using weather data as these insects are poikilothermic (Okpara, 2018). Morphological analysis also can be used to estimate age; however, it is more difficult with pupal samples as the pupae exterior does not change significantly as development progresses (Bala & Sharma, 2016). Gene regulation analysis can estimate the age of samples. MicroRNAs are short noncoding RNA that regulate gene expression (Cannell et al., 2008). Here, we aim to catalog miRNAs expressed during the development of three forensically relevant blow fly species preserved in several storage conditions. Results demonstrated that various miRNA sequences were differentially expressed across pupation. Expression of miR92b increased during mid pupation, aga-miR-92b expression increased during early pupation, and bantam, miR957, and dana-bantam-RA expression increased during late pupation. These results suggest that microRNA can be used to estimate the age of pupal samples as miRNA expression changes throughout pupation. Future work could develop a statistical model to accurately determine age using miRNA expression patterns.
Forensic entomology is an important field of forensic science that utilizes insect evidence in criminal investigations. Blow flies (Diptera: Calliphoridae) are among the first colonizers of remains and are therefore frequently used in determining the minimum postmortem interval (mPMI). Blow fly development, however, is influenced by a variety of factors including temperature and feeding substrate type. Unfortunately, dietary fat content remains an understudied factor on the development process, which is problematic given the relatively high rates of obesity in the United States. To study the effects of fat content on blow fly development we investigated the survivorship, adult weight and development of Lucilia sericata (Meigen; Diptera: Calliphoridae) and Phormia regina (Meigen; Diptera: Calliphoridae) on ground beef with a 10%, 20%, or 27% fat content. As fat content increased, survivorship decreased across both species with P. regina being significantly impacted. While P. regina adults were generally larger than L. sericata across all fat levels, only L. sericata demonstrated a significant (P < 0.05) difference in weight by sex. Average total development times for P. regina are comparable to averages published in other literature. Average total development times for L. sericata, however, were nearly 50 hours higher. These findings provide insight on the effect of fat content on blow fly development, a factor that should be considered when estimating a mPMI. By understanding how fat levels affect the survivorship and development of the species studied here, we can begin improving the practice of insect evidence analysis in casework.
