Does chewing xylitol gum improve oral health?

Popular chewing gum brands such as Orbit and Trident advertise that chewing their gum promotes oral health due to the presence of xylitol. This compound has interested oral health researchers since the 1970 s, but recent advances in research have been used to market it to the public as a prophylactic. Xylitol is a sugar that cannot be fermented by virtually any bacterial species, including Streptococcus mutans (S. mutans), the main contributor to dental caries (tooth cavities). The sugar alcohol negatively affects the pathogen in two different ways: it decreases plaque adhesiveness and inhibits growth. I have analyzed experiments from leading oral health researchers that aimed to determine how xylitol affects S. mutans, the optimal dose of xylitol for S. mutans inhibition, short-term and long-term benefits of xylitol, and limitations of xylitol being sold to different socioeconomic classes. While legitimate platforms for xylitol distribution still need to be expanded, the benefits of xylitol are literally worth salivating over. As governments look to improve health care practices for their citizens, xylitol products should be considered as a legitimate means of reducing oral health maladies.Honors CollegeThesis (B.?.

Estimating Returns to Schooling When Schooling is Misreported

We propose a general method of moments technique to identify measurement error in self-reported and transcript-reported schooling using differences in wages, test scores, and other covariates to discern the relative verity of each measure. We also explore the implications of such reporting errors for both OLS and IV estimates of the returns to schooling. The results cast a new light on two common findings in the extensive literature on the returns to schooling: sheepskin effects' and the recent IV estimates, relying on natural experiments' to identify the payoff to schooling. First, respondents tend to self-report degree attainment much more accurately than they report educational attainment not corresponding with degree attainment. For instance, we estimate that more than 90 percent of those with associate's or bachelor's degrees accurately report degree attainment, while only slightly over half of those with 1 or 2 years of college credits accurately report their educational attainment. As a result, OLS estimates tend to understate returns per year of schooling and overstate degree effects. Second, because the measurement error in educational attainment is non-classical, IV estimates also tend to be biased, although the magnitude of the bias depends upon the nature of the measurement error in the region of educational attainment affected by the instrument.

Paying for performance: the education impacts of a community college scholarship program for low-income adults

We evaluate educational outcomes from an experiment which randomly assigned performancebased scholarship eligibility to students on community college campuses. Scholarships were awarded in three payments each semester over the course of two semesters. Payments were tied to students meeting two conditions—enrolling at least half time and maintaining a “C” or better semester grade point average. We find that the program increased the likelihood a student was enrolled at the program institutions in both the first and second semesters after random assignment and increased the total number of credits attempted and earned each semester. One year after random assignment, program group students were more likely to persist at their program institution, and one and two years after random assignment, program group students had completed 3-4 credits more than the control group students. We find little evidence that program eligibility induced students to change the types of courses taken but some evidence that the program may have increased academic performance and effort conditional on enrollment.Education - Economic aspects ; Income

Rewarding Persistence: Effects of a Performance-Based Scholarship Program for Low-Income Parents

This report describes the impacts of a performance-based scholarship program with a counseling component on academic success and persistence among low-income parents. Students who participated in the program, which was operated at two New Orleans-area colleges as part of MDRC's multisite Opening Doors demonstration, were more likely to stay in school, get higher grades, and earn more credits

The relative effect of charge dimensions on elastic vibration attenuation and blast-induced seismic energy concepts

This dissertation focuses on expanding the blasting industry\u27s current understanding of the effect of charge geometry on blast vibration attenuation. The work includes a multiple regression analysis of a sample population of signature hole blast vibration data. The regression analysis is used to identify the relative effect of the variables that affect blast vibrations at various distances from the charge. The study suggests that the most common vibration models used in the blasting industry do not use all of the statistically significant variables. Therefore, the models neglect to fully describe the relationship between the significant variables and the blast vibration. The results of the statistical study are used as a foundation for a new method of analyzing and presenting blast vibration data that does fully describe this relationship. Currently, the blasting industry relies on variations of the scaled distance equation and the Z-Curve to predict or illustrate blast vibration characteristics. These methods focus on blast vibration amplitude and frequency, charge weight, and the distance from the charge. However, neither method solely accounts for all of these details. Additionally, both methods omit variables that have a statistically significant effect on blast vibration attenuation. This document shows that the current methods can be improved upon by developing a methodology that focuses on blast vibration energy. Energy, which can account for blast vibration amplitude, frequency, and duration, can be related to all of the statistically significant variables. Energy relationships also have an advantage over the traditional methods since energy is more easily understood by the general public. --Abstract, page iii

The mitigation effects of a barrier wall on blast wave pressures

The study examined the mitigating effects of a blast barrier wall. This area of blast mitigation is of interest due to the many different applications involved in protecting a specific target from an explosive attack. The research follows a 1:50 scale layout using 73 gram, hemisphere-shaped, Composition-4 charges detonated at combinations of three standoff distances from a blast barrier wall set at three different heights. This project used 45 data points for each combination of standoff distance and wall height. This project expanded prior research conducted by the United States Army Corps of Engineers (USACE) by increasing the database of recorded pressures behind a barrier wall and finding that a barrier wall creates an elongated effect on the pressure reduction area behind the wall. In other words, the pressure reduction area extends more along the wall than it does away from the wall. The results of further study indicate how and to what extent the wall affects the pressures created by the detonation of the Composition-4 hemispheres in the regions selected. The distance at which the blast pressures were mitigated was affected by the wall height and standoff distance. The wall height had a greater impact on the extent of the percent pressure reduction than did the standoff distance; however, the standoff distance has the greatest effect on the magnitude of the pressures behind a barrier wall. In the end, it is hoped that the analysis contained in this thesis will aid in future investigations of blast barrier walls and lead to more in-depth analyses and the creation of more complex models to predict the effects of blast barrier walls on detonation shocks and pressures from charges detonated at finite distances from the walls --Abstract, page iii

The Trauma Registry Compared to All Patient Refined Diagnosis Related Groups (APR DRG)

Background Literature has shown there are significant differences between administrative databases and clinical registry data. Our objective was to compare the identification of trauma patients using All Patient Refined Diagnosis Related Groups (APR-DRG) as compared to the Trauma Registry and estimate the effects of those discrepancies on utilization. Methods Admitted pediatric patients from 1/2012–12/2013 were abstracted from the trauma registry. The patients were linked to corresponding administrative data using the Pediatric Health Information System database at a single children’s hospital. APR-DRGs referencing trauma were used to identify trauma patients. We compared variables related to utilization and diagnosis to determine the level of agreement between the two datasets. Results There were 1942 trauma registry patients and 980 administrative records identified with trauma-specific APR-DRG during the study period. Forty-two percent (816/1942) of registry records had an associated trauma-specific APR-DRG; 69% of registry patients requiring ICU care had trauma APR-DRGs; 73% of registry patients with head injuries had trauma APR-DRGs. Only 21% of registry patients requiring surgical management had associated trauma APR-DRGs, and 12.5% of simple fractures had associated trauma APR-DRGs. Conclusion APR-DRGs appeared to only capture a fraction of the entire trauma population and it tends to be the more severely ill patients. As a result, the administrative data was not able to accurately answer hospital or operating room utilization as well as specific information on diagnosis categories regarding trauma patients. APR-DRG administrative data should not be used as the only data source for evaluating the needs of a trauma program

Identification and characterization of MUS81 point mutations that abolish interaction with the SLX4 scaffold protein

AbstractMUS81-EME1 is a conserved structure-selective endonuclease with a preference for branched DNA substrates in vitro that correspond to intermediates of DNA repair. Cells lacking MUS81 or EME1 show defects in the repair of DNA interstrand crosslinks (ICL) resulting in hypersensitivity to agents such as mitomycin C. In metazoans, a proportion of cellular MUS81-EME1 binds the SLX4 scaffold protein, which is itself instrumental for ICL repair. It was previously reported that mutations in SLX4 that abolished interaction with MUS81 affected ICL repair in human cells but not in murine cells. In this study we looked the other way around by pinpointing amino acid residues in MUS81 that when mutated abolish the interaction with SLX4. These mutations fully rescued the mitomycin C hypersensitivity of MUS81 knockout murine cells, but they were unable to rescue the sensitivity of two different human cell lines defective in MUS81. These data support an SLX4-dependent role for MUS81 in the repair, but not the induction of ICL-induced double-strand breaks. This study sheds light on the extent to which MUS81 function in ICL repair requires interaction with SLX4

Trends in pediatric adjusted shock index predict morbidity and mortality in children with severe blunt injuries

Purpose The utility of measuring the pediatric adjusted shock index (SIPA) at admission for predicting severity of blunt injury in pediatric patients has been previously reported. However, the utility of following SIPA after admission is not well described. Methods The trauma registry from a level-one pediatric trauma center was queried from January 1, 2010 to December 31, 2015. Patients were included if they were between 4 and 16 years old at the time of admission, sustained a blunt injury with an Injury Severity Score ≥ 15, and were admitted less than 12 h after their injury (n = 286). Each patient's SIPA was then calculated at 0, 12, 24, 36, and 48 h after admission and then categorized as elevated or normal at each time frame based upon previously reported values. Trends in outcome variables as a function of time from admission for patients with an abnormal SIPA to normalize as well as patients with a normal admission SIPA to abnormal were analyzed. Results In patients with a normal SIPA at arrival, 18.4% of patients who developed an elevated SIPA at 12 h after admission died, whereas 2.4% of patients who maintained a normal SIPA throughout the first 48 h of admission died (p < 0.01). Among patients with an elevated SIPA at arrival, increased length of time to normalize SIPA correlated with increased length of stay (LOS) and intensive care unit (ICU) LOS. Similarly, elevation of SIPA after arrival in patients with a normal initial SIPA correlated to increased LOS and ICU LOS. Conclusions Patients with a normal SIPA at time of arrival who then have an elevated SIPA in the first 24 h of admission are at increased risk for morbidity and mortality compared to those whose SIPA remains normal throughout the first 48 h of admission. Similarly, time to normalize an elevated admission SIPA appears to directly correlate with LOS, ICU LOS, and other markers of morbidity across a mixed blunt trauma population. Whether trending SIPA early in the hospital course serves only as a marker for injury severity or if it has utility as a resuscitation metric has not yet been determined

Assessment of the Placental Cord Insertion Using 3‐Dimensional Ultrasound at the Time of the Structural Fetal Survey

Objectives The influence of placental morphologic characteristics on pregnancy outcomes is poorly understood. Our objective was to evaluate the relationship of the distance of the placental cord insertion from the placental edge (PCI‐D) with associated placental characteristics as well as birth outcomes. Methods We performed a retrospective cohort study of nulliparous women with singleton gestations undergoing obstetric ultrasound examinations between 14 and 23 weeks’ gestation with a cervical length of greater than 3.0 cm who delivered between 24 and 42 weeks. A 3‐dimensional volume of the placenta was evaluated. The PCI‐D was obtained with Virtual Organ computer‐aided analysis software (GE Healthcare, Milwaukee, WI). Generalized linear regression and generalized additive models were fitted to explore the associations between the PCI‐D in relation to demographic and clinical characteristics. Results A total of 216 pregnancies were included in the analysis. The PCI‐D did not correlate with maternal age, gestational age at delivery, mode of delivery, or 5‐minute Apgar score. Although not statistically significant, the birth weight z score (P = .09) was associated with a longer PCI‐D, and gravidity was associated with a shorter PCI‐D (P = .10). A low‐lying placenta or placenta previa was associated with a longer PCI‐D (P = .03). Conclusions The PCI‐D is associated with a low placental position in the second trimester. These data are helpful for understanding placental development. The PCI‐D may be associated with pregnancy‐related factors such as birth weight and multigravidity. More research is required to evaluate the effects of pregnancy‐related factors on the PCI‐D and the effect of the PCI‐D on pregnancy outcomes