Master of Science

thesisAn ever-present challenge at most active mining operations is controlling blastinduced damage beyond design limits. Implementing more effective wall control during blasting activities requires (1) understanding the damage mechanisms involved and (2) reasonably predicting the extent of blast-induced damage. While a common consensus on blast damage mechanisms in rock exists within the scientific community, there is much work to be done in the area of predicting overbreak. A new method was developed for observing near-field fracturing with a borescope. A field test was conducted in which a confined explosive charge was detonated in a body of competent rhyolite rock. Three instrumented monitoring holes filled with quick-setting cement were positioned in close proximity to the blasthole. Vibration transducers were secured downhole and on the surface to measure near-field vibrations. Clear acrylic tubing was positioned downhole and a borescope was lowered through it to view fractures in the grout. Thin, two-conductor, twisted wires were placed downhole and analyzed using a time-domain reflectometer (TDR) to assess rock displacement. Fracturing in the grout was easily observed with the borescope up to 3.78 m (12.4 ft) from the blasthole, with moderate fracturing visible up to 2.10 m (6.9 ft). Measured peak particle velocities (PPV) at these distances were 310 mm/s (12.2 in./s) and 1,490 mm/s (58.5 in./s), respectively, although no fracturing was observed near the depth of the vibration transducers located 3.78 m (12.4 ft) from the blasthole. TDR readings were difficult to interpret but indicated rock displacement in two of the monitoring holes. Three methods were used to predict the radial extent of tensile damage around the blasthole: a modified Holmberg-Persson (HP) model, a shockwave transfer (SWT) model, and a dynamic finite element simulation using ANSYS AutodynTM. The extent of damage predicted by the HP and SWT models is similar to field measurements when using static material properties of the rock, but is underestimated using dynamic material properties. The Autodyn™ model significantly overpredicted the region of damage but realistically simulated the zones of crushing and radial cracking. Calibration of material parameters for the AutodynTM model would be needed to yield more accurate results

Henry Hughes Interview 2017

This is a brief interview detailing Henry Hughes’s experiences as a Professor in the English department at Western Oregon University. In the interview, Professor Hughes answers questions regarding his time here at Western with the students and faculty

Cyberinfrastructure for Cosmology and Line-of-Sight Projection in Optical Galaxy Clusters.

Upcoming wide-area sky surveys such as the Dark Energy Survey (DES) offer the power to test the source of cosmic acceleration by placing extremely precise constraints on existing cosmological model parameters. These observational surveys will employ multiple tests based on statistical signatures of galaxies and larger-scale structures such as clusters of galaxies. Simulations of large-scale structure provide the means to maximize the power of sky survey tests by characterizing key sources of systematic uncertainties. This dissertation explores two subjects motivated by these facts. First, it explores how grid-aware cyberinfrastructure needs to be utilized in current and upcoming simulation campaigns that support large-area sky surveys. Second, it shows how line-of-sight projection plays into cosmological analysis based on galaxy cluster counts in the same wide-area sky surveys. In the first part, an Apache Airavata-enabled grid-aware application workflow for managing simulations is described. Results pertaining to efficiency in producing N-body simulations are reported. In the second part, bias in cosmological parameter estimates caused by incorrectly assuming a Gaussian (projection-free) mass--observable relation when the true relation is non-Gaussian due to projection is explored. Projection tends to skew the mass--observable relation of galaxy clusters by creating a small fraction of severely blended systems, those for which the measured observable property of a cluster is strongly boosted relative to the value of its primary host halo. A model motivated by optical cluster-finding applied to the Millennium Simulation is introduced for projection and Fisher information matrix parameter bias forecasts are produced for a DES-like sky survey. The model predicts significant biases in the dark energy density and equation of state parameters. The model additional predicts an increase in uncertainties in dark energy parameters to a factor of about two larger than forecast uncertainties. Additionally, new parameters used to characterize the model degrade uncertainties in the dark energy parameters. Motivated by this result, this dissertation also contains preliminary results for a new projection model meant to reduce bias in cluster analysis based on redMaPPer identified clusters for the DES.PHDPhysicsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/99938/1/bmse_1.pd

Evaluation of Rotator Cuff Repair with Concomitant Biceps Tenodesis

Introduction: Surgical rotator cuff repair (RCR) has proven to be an effective treatment for rotator cuff tears. Commonly, rotator cuff tears are associated with concomitant biceps pathology, which are often treated by biceps tenodesis (BT). We hypothesize that patient outcomes will be similar in those that have undergone RCR with concomitant BT and isolated RCR. Methods: This is a retrospective cohort study comparing patients who underwent arthroscopic RCR with arthroscopic or open BT to patients who underwent isolated RCR at a multisurgeon orthopaedic practice during the time period of November 2016 to December 2016. The outcome for comparison is the American Shoulder and Elbow Surgeons score (ASES). Patients with postoperative scores of at least 6 months after surgery were included. The data was collected from the Rothman Institute registry and OBERD. It was analyzed via independent t-test. Results: A total of 53 patients (37 = M; 16 = F) were in the isolated RCR group and 34 patients (27 = M; 7 = F) were in the RCR with BT group. The average age in the isolated RCR group was 58.6 years vs. 58.9 years in the RCR with BT group. There was no statistical difference between postoperative ASES scores (83.69 and 79.43, P = .40) and difference in preoperative and postoperative ASES scores (34.26 and 35.30, P = .85) in the isolated RCR and RCR with BT groups, respectively. Conclusion: There was no significant difference in postoperative ASES scores as well as difference in preoperative and postoperative ASES scores in patients undergoing isolated RCR and RCR with BT. This supports the hypothesis that patients undergoing RCR with BT will have similar outcomes to those undergoing isolated RCR

A High Throughput Workflow Environment for Cosmological Simulations

The next generation of wide-area sky surveys offer the power to place extremely precise constraints on cosmological parameters and to test the source of cosmic acceleration. These observational programs will employ multiple techniques based on a variety of statistical signatures of galaxies and large-scale structure. These techniques have sources of systematic error that need to be understood at the percent-level in order to fully leverage the power of next-generation catalogs. Simulations of large-scale structure provide the means to characterize these uncertainties. We are using XSEDE resources to produce multiple synthetic sky surveys of galaxies and large-scale structure in support of science analysis for the Dark Energy Survey. In order to scale up our production to the level of fifty 10^10-particle simulations, we are working to embed production control within the Apache Airavata workflow environment. We explain our methods and report how the workflow has reduced production time by 40% compared to manual management.Comment: 8 pages, 5 figures. V2 corrects an error in figure

Outpatient Total Shoulder Replacement Procedures

The number of total shoulder arthroplasty (TSA) and reverse total shoulder arthroplasty (RTSA) procedures performed each year has continued to rise. While these procedures were historically done in the inpatient setting, many surgeons have migrated to performing TSA and RTSA in the outpatient setting. This can either involve sending patients home the same day from the hospital or performing these in an outpatient center. Specific protocols should be followed in regard to patient selection to minimize the risk of complications and readmission. Similarly, a team approach between the anesthesiologist and the surgeon is critical to ensure adequate pain control. Use of tranexamic acid (TXA), a preoperative nerve block as well as specific combinations of preoperative and postoperative medications are helpful in creating an optimal environment in which to perform the shoulder arthroplasty for the patient. When done well, TSA and RTSA can successfully be performed as an outpatient with a very high success rate and a low risk of complications

Influence of Projection in Cluster Cosmology Studies

Projection tends to skew the mass-observable relation of galaxy clusters by creating a small fraction of severely blended systems, those for which the measured observable property of a cluster is strongly boosted relative to the value of its primary host halo. We examine the bias in cosmological parameter estimates caused by incorrectly assuming a Gaussian (projection-free) mass-observable relation when the true relation is non-Gaussian due to projection. We introduce a mixture model for projection and explore Fisher forecasts for a survey of 5000 sq. deg. to z=1.1 and an equivalent mass threshold of 10^13.7 h^-1 solar masses. Using a blended fraction motivated by optical cluster finding applied to the Millennium Simulation and applying Planck and otherwise weak priors, we find that the biases in Omega_DE and w are significant, being factors of 2.8 and 2.4, respectively, times previous forecast uncertainties. Incorporating eight new degrees of freedom to describe cluster selection with projection increases the forecast uncertainty in Omega_DE and w by similar factors. Knowledge of these additional parameters at the 5% level limits degradation in dark energy constraints to <10% relative to projection-free forecasts. We discuss strategies for using simulations and complementary observations to characterize the fraction of blended clusters and their mass selection properties.Comment: 11 pages, 4 figures to be submitted to phys. rev.

The Impact of Early Morning Training Sessions on Total Sleep Time in Collegiate Athletes

International Journal of Exercise Science 15(6): 423-433, 2022. Early morning training sessions may affect sleep quantity in athletes. The purpose of this study is to examine differences in total sleep time of collegiate athletes on nights prior to early morning training sessions relative to non-training nights. Wristwatch monitors equipped with photoplethysmography and accelerometer technology were worn by 18 NCAA Division III collegiate athletes (Age: 20.1 ± 1.6 years, Height: 1.81 ± 0.02 m, Body Mass: 91.2 ± 6.5 kg, Body Fat %: 20.8 ± 1.6%) during a two-week period of training to monitor total sleep times. Athletes recorded time in and out of bed using a sleep diary, anxiety levels due to having to wake up in the morning, and perceived recovery status (PRS) upon waking the next day. The data were divided into: nights before non-training days (NT) and Training days (TD). Data were analyzed using univariate analysis. All athletes obtained significantly less total sleep on nights before TD relative to NT (NT: 8:15 ± 1:03 vs. TD: 6:08 ± 0:59 hh:mm; p \u3c 0.05). There was a positive relationship between total sleep time and recovery status (p \u3c 0.01). Anxiety scores were inversely related to total sleep time (p \u3c 0.01). Next-day recovery status was inversely related to anxiety scores (p \u3c 0.001). College athletes obtained significantly less total sleep time on nights before early morning training sessions (\u3c 0700) during the off-season, regardless of sex and sport. Coaches should consider later training sessions or promote optimal sleep quantity in order to minimize the risks associated to early morning training sessions