Due to rapid developments of wearable and portable devices in recent years, displays with better efficiency and higher resolution performances are greatly desired. Inorganic micro-light-emitting diodes (μLEDs) have been considered as one of the promising candidates for next-generation display applications, and demonstrations of μLED displays have shown outstanding performances as compared to liquid crystal displays (LCDs) and organic-light-emitting-diode (OLED) displays. However, it has been shown that the maximum efficiency drops as the device dimensions shrink. This dissertation describes post-etch fabrication techniques that suppress or mitigate the size effect in InGaN and AlGaInP μLEDs.

In this dissertation, the concepts of current display technologies, namely LCDs and OLED displays, and μLEDs will be first introduced. Moreover, the mechanism of the reduction in efficiency will also be addressed. Followed by the first chapter, a series of fabrication methods and their improvements to the device performances will be discussed in the chapters 2-4. In chapter 2, the optoelectrical improvements in the InGaN μLEDs with dielectric sidewall passivation using atomic layer deposition (ALD) will be illustrated. This is the first demonstration that the InGaN μLED efficiency can be partially recovered using post-etch technique. Due to the greater surface recombination velocity and minority carrier diffusion length, the effects of ALD sidewall passivation on AlGaInP μLEDs are investigated in chapter 3. This chapter also reveals the excellent optical properties of AlGaInP red emitters, and the potential elimination of the size effect in AlGaInP devices is also shown. In chapter 4, a detailed report on the performances of InGaN devices with the combination of chemical treatment and ALD sidewall passivation is presented, where this is the first demonstration of size-independent efficiency from 100×100 to 10×10 μm2 devices. Since the size effect is mitigated in InGaN and AlGaInP devices, chapter 5 shows a possible mass transfer method that employs fluidic assembly with external forces. Lastly, other critical challenges in μLED displays, brief μLED device process follower, and outlook are discussed concisely in chapter 6.

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Background: Syncope has myriad etiologies, ranging from benign to immediately life threatening. This frequently leads to over testing. Chest x-rays are among these commonly performed tests despite their uncertain diagnostic yield.

Objectives: To quantify the distribution of normal and abnormal chest x-rays in patients presenting with a chief complaint of syncope, stratified by those who did or did not have an adverse event at thirty days.

Methods: Prospective cohort of consecutive patients presenting to an urban tertiary care academic medical center with a chief complaint of syncope from 2003-2006.  The frequency and findings for each CXR were reviewed, as well as ED and hospital discharge diagnoses as well as thirty-day outcome.

Results: There were 575 total subjects, 39.7% were male, and the mean age was 57.2 (SD 24.6).  Of the 575 total subjects, 403 (70.1%) had chest x-rays performed, and 116 (20.2%) had an adverse event after their syncope.  Of the 116 people who had an adverse event, 15 (12.9%) had a positive CXR, 81 (69.8%) had a normal CXR, and 20 (17.2%) did not have a CXR as part of the initial evaluation.  Among the 459 people who did not have an adverse event 3 (0.7%) had a positive CXR, 304 (66.2%) had a normal CXR, and 152 (33.1%) did not have a CXR performed.

Conclusions:  Among patient who had an adverse event after their syncope, the majority of patients had a normal CXR.  More data is needed to validate this conclusion.

Introduction: Frequent thrombotic complications have been reported in patients with severe coronavirus disease 2019 (COVID-19) infection. The risk in patients with mild disease is unknown.

Case Report: We report a case series of three individuals recently diagnosed with COVID-19, who presented to the emergency department with chest pain and were found to have pulmonary emboli. The patients had mild symptoms, no vital sign abnormalities, and were negative according to the pulmonary embolism rule-out criteria.

Conclusion: This suggests that patients with active or suspected COVID-19 should be considered at elevated risk for pulmonary embolism when presenting with chest pain, even without common risk factors for pulmonary embolism.

Epiglottitis is an uncommon but life-threatening disease. While the most common infectious causesare the typical respiratory pathogens, Pasteurella multocida is a rare causative organism. Wepresent a case of P. multocida epiglottitis diagnosed by blood culture. The patient required intubationbut was successfully treated medically. P. multocida is a rare cause of epiglottitis; this is the ninthreported case in the literature. Most diagnoses are made from blood culture and patients usuallyhave an exposure to animals.

Introduction: Resident productivity is an important educational and operational measure in emergency medicine (EM). The ability to continue effectively seeing new patients throughout a shift is fundamental to an emergency physician’s development, and residents are integral to the workforce of many academic emergency departments (ED). Our previous work has demonstrated that residents make gains in productivity over the course of intern year; however, it is unclear whether this is from experience as a physician in general on all rotations, or specific to experience in the ED.

Methods: This was a retrospective cohort study, conducted in an urban academic hospital ED, with a three-year EM training program in which first-year residents see new patients ad libitum. We evaluated resident shifts for the total number of new patients seen. We constructed a generalized estimating equation to predict productivity, defined as the number of new patients seen per shift, as a function of the week of the academic year, the number of weeks spent in the ED, and their interaction. Off-service residents’ productivity in the ED was analyzed in a secondary analysis.

Results: We evaluated 7,779 EM intern shifts from 7/1/2010 to 7/1/2016. Interns started at 7.16 (95% confidence interval [CI] [6.87 – 7.45]) patients per nine-hour shift, with an increase of 0.20 (95% CI [0.17 – 0.24]) patients per shift for each week in the ED, over 22 weeks, leading to 11.5 (95% CI [10.6 – 12.7]) patients per shift at the end of their training in the ED. The effects of the week of the academic year and its interaction with weeks in the ED were not significant. We evaluated 2,328 off-service intern shifts, in which off-service residents saw 5.43 (95% CI [5.02 – 5.84]) patients per nine-hour shift initially, with 0.46 additional patients per week in the ED (95% CI [0.25 – 0.68]). The weeks of the academic year were not significant.

Conclusion: Intern productivity in EM correlates with time spent training in the ED, and not with experience on other rotations. Accordingly, an EM intern’s productivity should be evaluated relative to their aggregate time in the ED, rather than the time in the academic year.