Three Essays in Employee Mobility

This dissertation studies employer and employee outcomes that are related to employee mobility. In particular, it explores the consequences of employee mobility on employer performance, and how constraints on employee mobility can affect employee welfare. The first two chapters investigate how quitting, and firing, of employees are associated with the employer’s future growth. The third chapter examines how mobility constraints in the form of the enforceability of covenants-not-to-compete (CNCs) affect employee mobility and wages. In the first chapter, I examine how the effect of worker quits on future establishment growth varies by the quitting worker’s productivity level. I argue that when there are labor market frictions related to search and training, the difficulty of replacing a worker with another of equivalent productivity increases with the productivity level of the quitting worker, and this in turn leads to greater detrimental effect of quits by higher productivity workers. I provide novel empirical evidence that quits of high productivity workers lower future growth, whereas quits of low productivity workers do not. In particular, a one standard deviation increase in quit rate of high productivity workers is associated with a 1.2 percentage point decline in future establishment employment growth rate. The detrimental effect of high productivity worker quits is stronger for establishments with higher replacement costs: establishments that are more likely to have unfilled vacancies, that are more likely to cover the training costs of their employees, that have a more knowledge-intensive workforce, that have more complex operations, and that have worker representatives participating in hiring decisions. I exploit the richness of the German employer-employee linked data to distinguish quitting workers from fired workers, and construct instrumental variables to alleviate potential endogeneity concerns. This study contributes to the literature by exploring the role of replacement-related frictions in mediating the relation between worker quits and establishment performance. The second chapter examines how firing as a management practice can enhance worker-firm idiosyncratic match quality, and thereby foster growth of small firms. I view match quality as a component of a worker’s productivity contribution to the firm, determined by the fit between the worker and the firm. Utilizing German employer-employee linked data, I propose a measure of match quality and examine how firing, match quality, and growth are related at the firm-level. I hypothesize that firms can enhance its match quality with its workforce by trying out different workers, and find that firing is positively associated with enhanced match quality and stronger future growth. This relation is stronger for firing workers with fewer number of past jobs. In the third chapter, we examine the relationship between the enforceability of covenants-not-to-compete (CNCs), and employee mobility and wages. Using matched employer-employee data, we find that workers starting a job in an average-enforceability state experience longer job spells and lower wages such that after 8 years they have about 8% fewer jobs and 5% lower cumulative earnings relative to equivalent workers in a non-enforcing state. We then examine the 2015 CNC ban for tech workers in Hawaii and find that this ban increased mobility by 11% and new-hire wages by 4%. These results are consistent with CNC enforceability increasing monopsony power.PHDBusiness AdministrationUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/147567/1/jinwooch_1.pd

Locked in? The Enforceability of Covenants Not to Compete and the Careers of High-Tech Workers

We examine how the enforceability of covenants not to compete (CNCs) affects employee mobility and wages of high-tech workers. We expect CNC enforceability to lengthen job spells and constrain mobility, but its impact on wages is ambiguous. Using a matched employer-employee dataset covering the universe of jobs in thirty U.S states, we find that higher CNC enforceability is associated with longer job spells (fewer jobs over time), and a greater chance of leaving the state for technology workers. Consistent with a “lock-in” effect of CNCs, we find persistent wage-suppressing effects that last throughout a worker’s job and employment history.http://deepblue.lib.umich.edu/bitstream/2027.42/136096/1/1339_Chang.pd

Localized Dielectric Loss Heating in Dielectrophoresis Devices

Temperature increases during dielectrophoresis (DEP) can affect the response of biological entities, and ignoring the effect can result in misleading analysis. The heating mechanism of a DEP device is typically considered to be the result of Joule heating and is overlooked without an appropriate analysis. Our experiment and analysis indicate that the heating mechanism is due to the dielectric loss (Debye relaxation). A temperature increase between interdigitated electrodes (IDEs) has been measured with an integrated micro temperature sensor between IDEs to be as high as 70 °C at 1.5 MHz with a 30 Vpp applied voltage to our ultra-low thermal mass DEP device. Analytical and numerical analysis of the power dissipation due to the dielectric loss are in good agreement with the experiment data

A Novel On-chip Three-dimensional Micromachined Calorimeter with Fully Enclosed and Suspended Thin-film Chamber for Thermal Characterization of Liquid Samples

A microfabricated calorimeter (μ-calorimeter) with an enclosed reaction chamber is presented. The 3D micromachined reaction chamber is capable of analyzing liquid samples with volume of 200 nl. The thin film low-stress silicon nitride membrane is used to reduce thermal mass of the calorimeter and increase the sensitivity of system. The μ-calorimeter has been designed to perform DC and AC calorimetry, thermal wave analysis, and differential scanning calorimetry. The μ-calorimeter fabricated with an integrated heater and a temperature sensor on opposite sides of the reaction chamber allows to perform thermal diffusivity and specific heat measurements on liquid samples with same device. Measurement results for diffusivity and heat capacitance using time delay method and thermal wave analysis are presented

Determining Adaptability Performance of Artificial Neural Network-Based Thermal Control Logics for Envelope Conditions in Residential Buildings

This is the publisher's version, also available electronically from http://www.mdpi.com/1996-1073/6/7/3548This study examines the performance and adaptability of Artificial Neural Network (ANN)-based thermal control strategies for diverse thermal properties of building envelope conditions applied to residential buildings. The thermal performance using two non-ANN-based control logics and two predictive ANN-based control logics was numerically tested using simulation software after validation. The performance tests were conducted for a two-story single-family house for various envelope insulation levels and window-to-wall ratios on the envelopes. The percentages of the period within the targeted ranges for air temperature, humidity and PMV, and the magnitudes of the overshoots and undershoots outside of the targeted comfort range were analyzed for each control logic scheme. The results revealed that the two predictive control logics that employed thermal predictions of the ANN models achieved longer periods of thermal comfort than the non-ANN-based models in terms of the comfort periods and the reductions of the magnitudes of the overshoots and undershoots. The ANN-based models proved their adaptability through accurate control of the thermal conditions in buildings with various architectural variables. The ANN-based predictive control methods demonstrated their potential to create more comfortable thermal conditions in single-family homes compared to non-ANN based control logics

Biomarkers of Oxidative Stress and Endogenous Antioxidants for Patients with Chronic Subjective Dizziness

As a neurotologic disorder of persistent non-vertiginous dizziness, chronic subjective dizziness (CSD) arises unsteadily by psychological and physiological imbalance. The CSD is hypersensitivity reaction due to exposure to complex motions visual stimuli. However, the pathophysiological features and mechanism of the CSD still remains unclearly. The present study was purposed to establish possible endogenous contributors of the CSD using serum samples from patients with the CSD. A total 199 participants were gathered and divided into two groups; healthy (n = 152, male for 61, and female for 91) and CSD (n = 47, male for 5, female for 42), respectively. Oxidative stress parameters such as, hydrogen peroxide and reactive substances were significantly elevated (p < 0.01 or p < 0.001), whereas endogenous antioxidant components including total glutathione contents, and activities of catalase and superoxide dismutase were significantly deteriorated in the CSD group (p < 0.01 or p < 0.001) as comparing to the healthy group, respectively. Serum levels of tumor necrosis factor -α and interferon-γ were significantly increased in the CSD participants (p < 0.001). Additionally, emotional stress related hormones including cortisol, adrenaline, and serotonin were abnormally observed in the serum levels of the CSD group (p < 0.01 or p < 0.001). Our results confirmed that oxidative stress and antioxidants are a critical contributor of pathophysiology of the CSD, and that is first explored to establish features of redox system in the CSD subjects compared to a healthy population

Bacteriophages reduce Yersinia enterocolitica contamination of food and kitchenware

Yersinia enterocolitica, the primary cause of yersiniosis, is one of the most important foodborne pathogens globally and is associated with the consumption of raw contaminated pork. In the current study, four virulent bacteriophages (phages), one of Podoviridae (fHe-Yen3-01) and three of Myoviridae (fHe-Yen9-01, fHe-Yen9-02, and fHe-Yen9-03), capable of infecting Y. enterocolitica were isolated and characterized. fHe-Yen9-01 had the broadest host range (61.3% of strains, 65/106). It demonstrated a latent period of 35 min and a burst size of 33 plague-forming units/cell, and was found to have a genome of 167,773 bp with 34.79% GC content. To evaluate the effectiveness of phage fHe-Yen9-01 against Y. enterocolitica 0:9 strain Ruokola/71, we designed an experimental model of the food market environment. Phage treatment after bacterial inoculation of food samples, including raw pork (4 degrees C, 72 h), ready-to-eat pork (26 degrees C, 12 h), and milk (4 degrees C, 72 h), prevented bacterial growth throughout the experiments, with counts decreasing by 1-3 logs from the original levels of 2-4 x 10(3) CFU/g or ml. Similarly, when artificially contaminated kitchen utensils, such as wooden and plastic cutting boards and knives, and artificial hands, were treated with phages for 2 h, bacterial growth was effectively inhibited, with counts decreasing by 1-2 logs from the original levels of ca 10(4) CFU/cm(2) or ml. To the best of our knowledge, this is the first report of the successful application of phages for the control of Y. enterocolitica growth in food and on kitchen utensils.Peer reviewe