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Background. There are roughly 300,000 rib fractures treated for in the United States each year. These represent 10-26% of thoracic trauma injuries and have about a 10% mortality rate. There is a common belief that mortality in rib fracture patients can be contributed to the diagnosis of pneumonia, but this study does not support that claim. Purpose. To determine the predictors of morbidity and mortality in rib fracture patients. Methods. Using a level 1 trauma center patient registry, we retrospectively analyzed all patients that were admitted with at least one rib fracture (n=1,344). All predictors were analyzed with linear regressions. Results. The average age of the patients was 55.48 ± 20.29 years old and ranged between 15 and 98. ISS (OR: 1.0508, p<0.001), bilateral fractures (OR: 1.9495, p = 0.009) and pulmonary contusion (OR: 1.7481, p = 0.022) were all significant predictors of pneumonia. The age of the patient (OR: 1.0467, p < 0.001), ISS (OR: 1.0585, p <0.001), having 6 or more fractured ribs (OR: 3.1450, p < 0.001), the presence of hemothorax (OR: 2.5063, p = 0.048), and the use of mechanical ventilation (OR: 13.2125, p < 0.001) were all significant predictors of mortality. Flail segments (OR: 1.9871, p = 0.067), ISS (OR: 1.1267, p < 0.001), pulmonary contusions (OR: 1.5329, p = 0.047), pneumothorax (OR: 1.4372, p =0.073) and pneumonia (OR: 21.4516, p < 0.001) are all predictors of requiring mechanical ventilation. Conclusion. There are many studies that indicate rib fracture patients who are diagnosed with pneumonia have a higher risk or mortality. With this in mind, the logical course of treatment would be to counteract the complications pneumonia brings as to reduce the risk or mortality. To do this, it is recommend the patient be put on mechanical ventilation. While this has been seen to help with pneumonia patients, this study provides evidence that health care professionals should look for ways to reduce the need for mechanical ventilation instead of using it to combat the pneumonia.

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<p> Ion implanted Bragg gratings integrated in rib waveguide structures were simulated, fabricated and characterized for the silicon-on-insulator (SOI) photonics platform. After selective silicon self-implantation, to an amorphizing dose of 2x10^15 ions/cm^2, the approximately 0.3 damage-induced increase in the refractive index provided the modulation mechanism necessary for the formation of a Bragg grating. The benefits of implanted Bragg gratings compared to the more widely utilized surface relief type gratings include planar surface retention, desirable for subsequent processing and wafer bonding, and a smaller depth of the index modulation, important for minimizing filtering bandwidths. To our knowledge, this is the first time ion implantation has been utilized to produce Bragg gratings integrated in an SOI rib waveguide. The benefits of using SOI for an optoelectronics platform include: cost minimization, reduced device size, and compatibility with silicon based microelectronics.</p> <p> Device performance was simulated using coupled mode theory (CMT) in conjunction with beam propagation methods (BPM), to determine transverse modal profiles for computing coupling coefficients and to determine geometric dimensions suitable to achieve adequate grating strength and single-mode operation. The Monte Carlo ion implantation simulator SUSPREM4, implementing the binary collision approximation (BCA), was used to determine the amorphous silicon grating profiles. Implanted grating devices were then fabricated into SOI having a 2.5 μm device layer and were optically characterized. For a grating length of 2100 μm and an implant energy of 60 keV, the extinction ratio of the resonant wavelength was found to be -18.11 dB and -0.87 dB for TE and TM polarizations respectively. The excess loss per unit length was measured to be 1.2 dB/mm for TE polarization and 0.6 dB/mm for TM polarization. After annealing the gratings at temperatures of up to 300 °C, used to annihilate low energy point defects responsible for absorption, it was found that the excess loss per unit length was reduced to 0.3 dB/mm for TE polarization. Compared to etched gratings with similar dimensions, it was determined that the strength of the implanted gratings was approximately 2.5 times stronger for grating lengths one third the length as result of mode-shifting due to the higher index of refraction. This is of great consequence to the miniaturization and densification of Bragg grating based devices in silicon photonics.</p> / Thesis / Master of Applied Science (MASc)

In order to protect gas turbine blades from hot gases exiting the combustor, several intricate external and internal cooling concepts are employed. High pressure stage gas turbine blades feature serpentine passages where rib turbulators are installed to enhance heat transfer between the relatively colder air bled off from the compressor and the hot internal walls. Most of the prior studies have been restricted to Reynolds number of 90000 and several studies have been carried out to determine geometrically optimized parameters for achieving high levels of heat transfer in this range of Reynolds number. However, for land-based power generation gas turbines, the Reynolds numbers are significantly high and vary between 105 and 106. Present study is targeted towards these high Reynolds numbers where traditional rib turbulator shapes and prescribed optimum geometrical parameters have been investigated experimentally. A steady-state liquid crystal thermography technique is employed for measurement of detailed heat transfer coefficient. Five different rib configurations, viz., 45 deg., V-shaped, inverse V-shaped, W-shaped and M-shaped have been investigated for Reynolds numbers ranging from 150,000 to 400,000. The ribs were installed on two opposite walls of a straight duct with aspect ratio of unity. For very high Reynolds numbers, the heat transfer enhancement levels for different rib shapes varied between 1.3 and 1.7 and the thermal hydraulic performance was found to be less than unity. / Master of Science

The purpose of this study was to develop material properties of human rib cortical bone using dynamic tension coupon testing. This study presents 117 human rib cortical bone coupon tests from six cadavers, three male and three female, ranging in age from 18 to 67 years old. The rib sections were taken from the anterior, lateral, and posterior regions on ribs 1 through 12 of each cadaver's rib cage. The cortical bone was isolated from each rib section with a low speed diamond saw, and milled into dog bone shaped tension coupons using a small computer numerical control machine. A high-rate servo-hydraulic Material Testing System equipped with a custom slack adaptor, to provide constant strain rates, was used to apply tension loads to failure at an average rate of 0.5 strains/sec. The elastic modulus, yield stress, yield strain, ultimate stress, ultimate strain, and strain energy density were determined from the resulting stress versus strain curves. The overall average of all cadaver data gives an elastic modulus of 13.9 GPa, a yield stress of 93.9 MPa, a yield strain of 0.883 %, an ultimate stress of 124.2 MPa, an ultimate strain of 2.7 %, and a strain energy density of 250.1 MPa-strain. For all cadavers, the plastic region of the stress versus strain curves was substantial and contributed approximately 60 strain % to the overall response and over 80 strain % in the tests with the 18 year old cadaver. The rib cortical bone becomes more brittle with increasing age, shown by an increase in the modulus (p < 0.01) and a decrease in peak strain (p < 0.01). In contrast to previous three-bending tests on whole rib and rib cortical bone coupons, there were no significant differences in material properties with respect to rib region or rib level. When these results are considered in conjunction with the previous three-point bending tests, there is regional variation in the structural response of the human rib cage, but this variation appears to be primarily a result of changes in the local geometry of each rib while the material properties remain nearly constant within an individual. / Master of Science

The objective of this study was to evaluate the effects of sex, loading rate, and age on the tensile and compressive material properties of human rib cortical bone over a wide range of subject demographics. Tension coupons were tested from sixty-one (n = 61) subjects (M = 32, F = 29) ranging in age from 17 to 99 years of age (Avg. = 56.4 +/- 26.2 yrs.). Compression samples were tested from thirty (n = 30) subjects (M = 19, F = 11) ranging in age from 18 to 95 years of age (Avg. = 49.0 +/- 23.9 yrs.). For each subject, one coupon/sample was tested to failure on a material testing system at a targeted strain rate of 0.005 strain/s, while a second coupon/sample was tested at 0.5 strain/s. A load cell was used to measure axial load for both the tension coupons and compression samples. An extensometer was used to measure displacement within the gage length of the tension coupons and a deflectometer was used to measure displacement of the compression samples. Tension data were obtained from fifty-eight (n = 58) coupons at 0.005 strain/s and fifty-eight (n = 58) coupons at 0.5 strain/s, with fifty-five (n = 55) matched pairs. Compression data were obtained from thirty (n = 30) compression samples at 0.005 strain/s and thirty (n = 30) samples at 0.5 strain/s. The elastic modulus, yield stress, yield strain, ultimate stress, elastic strain energy density (SED), plastic SED, and total SED were then calculated for each tensile and compression test. In addition, failure stress and failure strain were calculated for each tension test. There were no significant differences in the tensile material properties between sexes and no significant interactions between age and sex for either method of loading. In regard to the differences in tensile material properties with respect to loading rate, yield stress, yield strain, failure stress, ultimate stress, elastic SED, plastic SED, and total SED were significantly lower at 0.005 strain/s compared to 0.5 strain/s. All material properties were significantly lower at 0.005 strain/s compared to 0.5 strain/s in compression. Spearman correlation analyses showed that all tensile material properties had significant negative correlations with age at 0.005 strain/s except modulus. At 0.5 strain/s, all tensile material properties except yield strain had significant negative correlations with age. No significant correlations were observed in material properties with respect to advanced age in compression at either loading rate. Although the results revealed that the tensile material properties of human rib cortical bone varied significantly with respect to chronological age, the R2 values only ranged from 0.15 - 0.62, indicating that there may be other underlying variables that better account for the variance within a given population. Overall, this is the first study to analyze the effects of sex, loading rate, and age on tensile material properties of human rib cortical bone using a reasonably large sample size and the first study to test the compressive material properties of human rib cortical bone. The results of this study provide data that allows FEMs to better assess thoracic injury risk for all vehicle occupants. Additionally, this study provides the necessary data to more accurately model and assess differences in the material response of the rib cage for nearly all vehicle occupants of driving age. / Master of Science / The thorax is one of the most frequently injured body regions in motor vehicle collisions (MVCs), and severe thoracic injuries have been shown to increase mortality risk. Finite element models (FEMs) of the human body are frequently used to evaluate thoracic injury risk. However, the accuracy of these models is dependent on the biomechanical data used to validate them. Although the material properties of bone have been shown to vary with respect to age and loading rate, previous studies that have evaluated the material properties of human rib cortical bone were limited to a small number of subjects, a narrow age range, one loading rate, and one loading mode (tension). Therefore, the purpose of this study was to evaluate the effects of sex, age, and loading rate on the tensile and compressive material properties of rib cortical bone over a wide range of subject demographics. Tension coupons were tested from sixty-one (n = 61) subjects (M = 32, F = 29) ranging in age from 17 to 99 years (Avg. = 56.4 ± 26.2 years). Compression samples were tested from thirty (n = 30) subjects (M = 19, F = 11) ranging in age from 18 to 95 years (Avg. = 49.0 ± 23.9 years). For each subject, one coupon/sample was tested to failure on a material testing system at a targeted strain rate of 0.005 strain/s, while the other coupon was tested at 0.5 strain/s. A load cell was used to measure axial load for both the tension coupons and compression samples. An extensometer was used to measure displacement within the gage length of the tension coupons and a deflectometer was used to measure displacement of the compression samples. There were no significant differences in material properties between sexes and no significant interactions between age and sex for either method of loading. In regard to the differences in tensile material properties with respect to loading rate, yield stress, yield strain, failure stress, ultimate stress, elastic SED, plastic SED, and total SED were significantly lower at 0.005 strain/s compared to 0.5 strain/s. All material properties were significantly lower at 0.005 strain/s compared to 0.5 strain/s in compression. In regard to the effect of age, all tensile material properties had significant negative correlations with age at except the modulus at 0.005 strain/s and yield strain at 0.5 strain/s. No significant correlations were observed in material properties with respect to advanced age in compression at either loading rate. Overall, this is the first study to provide the tension and compression data needed to more accurately model and assess differences in the material response of the rib cage for nearly all vehicle occupants of driving age.

The National Highway Traffic Safety Administration (NHTSA) reported that in 2008 there were a total of 37,261 automotive related fatalities, 26,689 of which were vehicle occupants. It has been reported that in automotive collisions chest injuries rank second only to head injuries in overall number of fatalities and serious injuries. In frontal collisions, chest injuries constitute 37.6% of all AIS 3+ injuries, 46.3% of all AIS 4+ injuries, and 43.3% of all AIS 5+ injuries. In side impact collisions, it has been reported that thoracic injuries are the most common type of serious injury (AIS≥3) to vehicle occupants in both near side and far side crashes which do not involve a rollover. In addition, rib fractures are the most frequent type of thoracic injury observed in both frontal and side impact automotive collisions. Anthropomorphic test devices (ATDs), i.e. crash test dummies, and finite element models (FEMs) have proved to be integral tools in the assessment and mitigation of thoracic injury risk. However, the validation of both of these tools is contingent on the availability of relevant biomechanical data. In order to develop and validate FEMs and ATDs with improved thoracic injury risk assessment capabilities, it is necessary to generate biomechanical data currently not presented in the literature. Therefore, the purpose of this dissertation is to present novel material, structural, and global thoracic skeletal response data as well as quantify thoracic injury timing in both frontal belt loading and side impact tests using cadaveric specimens. / Ph. D.