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"Schaefer, Joseph"
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Urban allies : ten brand-new collaborative stories
These collaborative stories unite two beloved characters from two different urban fantasy series in each of ten electrifying new stories.
Book
Measurement of Interlaminar Tensile Strength and Elastic Properties of Composites Using Open-Hole Compression Testing and Digital Image Correlation
Advanced polymeric composites are increasingly used in high-performance aircraft structures to reduce weight and improve efficiency. However, a major challenge delaying the implementation of the advanced composites is the lack of accurate methods for material characterization. Accurate measurement of three-dimensional mechanical properties of composites, stress–strain response, strength, fatigue, and toughness properties, is essential in the development of validated analysis techniques accelerating design and certification of composite structures. In particular, accurate measurement of the through-thickness constitutive properties and interlaminar tensile (ILT) strength is needed to capture delamination failure, which is one of the primary failure modes in composite aircraft structures. A major technical challenge to accurate measurement of ILT properties is their strong sensitivity to manufacturing defects that often leads to unacceptable scatter in standard test results. Unacceptable failure mode in standard test methods is another common obstacle to accurate ILT strength measurement. Characterization methods based on non-contact full-field measurement of deformation have emerged as attractive alternative techniques allowing more flexibility in test configuration to address some of the limitations inherent to strain gauge-based standard testing. In this work, a method based on full-field digital image correlation (DIC) measurement of surface deformation in unidirectional open-hole compression (OHC) specimens is proposed and investigated as a viable alternative to assessing ILT stress–strain, strength, and fatigue properties. Inverse identification using a finite element model updating (FEMU) method is used for simultaneous measurement of through-thickness elastic constants with recovery of the maximum ILT stress at failure for characterization of strength and fatigue S–N curves.
Journal Article
CONVECTIVE-SCALE WARN-ON-FORECAST SYSTEM
The National Oceanic and Atmospheric Administration's (NOAA's) National Weather Service (NWS) issues warnings for severe thunderstorms, tornadoes, and flash floods because these phenomena are a threat to life and property. These warnings are presently based upon either visual confirmation of the phenomena or the observational detection of proxy signatures that are largely based upon radar observations. Convective-scale weather warnings are unique in the NWS, having little reliance on direct numerical forecast guidance. Because increasing severe thunderstorm, tornado, and flash-flood warning lead times are a key NOAA strategic mission goal designed to reduce the loss of life, injury, and economic costs of these high-impact weather phenomena, a new warning paradigm is needed in which numerical model forecasts play a larger role in convective-scale warnings. This new paradigm shifts the warning process from warn on detection to warn on forecast, and it has the potential to dramatically increase warning lead times.
A warn-on-forecast system is envisioned as a probabilistic convective-scale ensemble analysis and forecast system that assimilates in-storm observations into a high-resolution convection-resolving model ensemble. The building blocks needed for such a system are presently available, and initial research results clearly illustrate the value of radar observations to the production of accurate analyses of convective weather systems and improved forecasts. Although a number of scientific and cultural challenges still need to be overcome, the potential benefits are significant. A probabilistic convective-scale warn-on-forecast system is a vision worth pursuing.
Journal Article
The Impact of El Niño–Southern Oscillation (ENSO) on Winter and Early Spring U.S. Tornado Outbreaks
In recent years, the potential of seasonal outlooks for tornadoes has attracted the attention of researchers. Previous studies on this topic have focused mainly on the influence of global circulation patterns [e.g., El Niño–Southern Oscillation (ENSO), North Atlantic Oscillation, or Pacific decadal oscillation] on spring tornadoes. However, these studies have yielded conflicting results of the roles of these climate drivers on tornado intensity and frequency. The present study seeks to establish linkages between ENSO and tornado outbreaks over the United States during winter and early spring. These linkages are established in two ways: 1) statistically, by relating raw counts of tornadoes in outbreaks (defined as six or more tornadoes in a 24-h period in the United States east of the Rocky Mountains), and their destructive potential, to sea surface temperature anomalies observed in the Niño-3.4 region, and 2) qualitatively, by relating ENSO to shifts in synoptic-scale atmospheric phenomena that contribute to tornado outbreaks. The latter approach is critical for interpreting the statistical relationships, thereby avoiding the deficiencies in a few of the previous studies that did not provide physical explanations relating ENSO to shifts in tornado activity. The results suggest that shifts in tornado occurrence are clearly related to ENSO. In particular, La Niña conditions consistently foster more frequent and intense tornado activity in comparison with El Niño, particularly at higher latitudes. Furthermore, it is found that tornado activity changes are tied not only to the location and intensity of the subtropical jet during individual outbreaks but also to the positions of surface cyclones, low-level jet streams, and instability axes.
Journal Article
The Correlation between U.S. Tornadoes and Pacific Sea Surface Temperatures
The correlation between tornadic activity in several regions of the United States and the monthly mean sea surface temperature over four zones in the tropical Pacific Ocean is examined. Tornadic activity is gauged with two mostly independent measures: the number of tornadoes per month, and the number of tornadic days per month. Within the assumptions set forth for the analysis, it is found that there appears to exist a statistically significant but very weak correlation between sea surface temperature in the Pacific Ocean and tornadic activity in the United States, with the strength and significance of the correlation depending on the coordinates at which the sea surface temperatures are assessed and the geographic region of the United States. The strongest evidence found is for the correlation between the number of days with strong and violent (F2 and greater) tornadoes in an area that runs from Illinois to the Atlantic Coast, and Kentucky to Canada and a cool sea surface temperature in the central tropical Pacific. However, there is only about a 53% chance of this relationship occurring in a specific month.
Journal Article
Entrepreneurs Want More Than Just Money: The Role of Subjective Entrepreneurial Success in Predicting Entrepreneur’s Grief Following Venture Failure
The focal topics of this dissertation are subjective entrepreneurial success (SES) and grief. Over the past three decades, the budding SES literature has seen accelerating growth since its conceptual inception in 1987, with 2016 marking a key event in the literature – the formal naming and definition of the SES construct. Research on the SES construct is of interest to scholars because it complements the objective economic conceptualizations of success often seen in the entrepreneurship literature, highlighting the idiosyncratic ways that entrepreneurs conceptualize and evaluate their success. To contribute to the SES literature, Essay One of my three-essay dissertation, I systematically review the SES literature. Second, I analyze the current state of the SES literature, showing what work scholars have done to examine SES and what journals have published it. Finally, I review the future directions that scholars have proposed in SES works, I highlight avenues for fruitful research.In Essay Two, I develop a set of three entrepreneurial striving types based on unique combinations of entrepreneurs’ personal values and the subjective success criteria that represent. I examine the potential for conflict and compatibility between these values and their representative criteria, and the potential effects on entrepreneurs’ motivation, well-being, and success. In Essay Three, I examined entrepreneurs’ grief following business failure and how this affects their intentions to create new businesses, and the effect that entrepreneurial identity and resilience may have on these relationships.
Dissertation
Twice‐Daily Doravirine Overcomes the Interaction Effect from Once‐Weekly Rifapentine and Isoniazid in Healthy Volunteers
Doravirine (DOR) is a non‐nucleoside reverse transcriptase inhibitor indicated for the treatment of HIV‐1. Its use in combination with rifapentine (RPT), an antituberculosis (TB) antibiotic, may reduce the exposure of DOR compromising viral suppression in those living with HIV‐1 co‐infected with TB. We conducted a prospective, phase I, open label, two‐period, fixed sequence, drug interaction study to evaluate the effect of once‐weekly RPT and isoniazid (INH) on the pharmacokinetics (PKs) of DOR in healthy volunteers. DOR 100 mg was administered alone twice‐daily for 4 days in period 1. In period 2, once‐weekly RPT + INH were co‐administered with multiple doses of DOR 100 mg twice‐daily for study days 7, 14, and 21. Plasma was obtained for DOR PKs when given alone and co‐administered with RPT + INH. Eleven healthy volunteers enrolled and completed the study. The geometric mean ratios and 90% confidence intervals for DOR area under the concentration‐time curve from zero to 12 hours (AUC0–12) and C12 in the presence of RPT + INH compared with DOR alone were 0.71 (0.60–0.85) and 0.69 (0.54–0.89), respectively. Although exposures were moderately reduced in the presence of RPT + INH, trough DOR values were within the concentration range associated with virological suppression. These results demonstrate that a modest decrease in DOR exposure would unlikely be clinically relevant in a virally suppressed patient co‐administered once‐weekly RPT + INH.
Journal Article
Rescue stenting for acute ischemic stroke with refractory emergent large vessel occlusion in the modern thrombectomy era
Rescue stenting is used as a bailout technique during mechanical thrombectomy for stroke. We performed a retrospective study analyzing outcomes of patients that received a stent as a bailout measure and compared results to a control group.
We identified all patients who underwent a mechanical thrombectomy for a large vessel occlusion between January 2010 and October 2019. Subjects with mTICI 0–2 A after at least three passes were defined as failed MT and constituted the control group (NSG-controls). Patients that received a rescue stent (RSG) formed the study group.
Comparative analysis of patient demographics between NSG-controls and SRG was performed. Baseline characteristics and comorbidities were not significantly different between both groups. NIHSS at admission and IV t-PA were not significantly different among both groups (16.5 vs. 14.2, p = 0.19) and (39.4% vs. 29.4%, p = 0.30), respectively. There was no significant difference in procedural and post-procedural complications between both the groups. In the RSG, 24 patients (82.4%) achieved favorable revascularization outcomes. NIHSS at discharge (p = 0.01) was higher in the NSG-controls, while favorable functional outcome at three months (12% vs. 39.2%, p = 0.01) was observed at a higher proportion in the RSG. There was also a significant mortality difference, with 15.2% mortality in the RSG compared to 35.1% mortality in the NSG-controls (p = 0.03). In multivariate analysis, stenting was an independent predictor of favorable outcome (OR: 10.0, p = 0.009).
Herein, we demonstrated that rescue stenting is a feasible, safe, and effective procedure to improve stroke outcomes and should be seriously considered if the primary mechanical thrombectomy is not successful.
•NIHSS at discharge (p = 0.01) was higher in the NSG, while favorable functional outcome at three months (12% vs. 39.2%, p = 0.01) was observed at a higher proportion in the rescue stenting group.•There was also a significant mortality difference, with 15.2% mortality in the rescue stenting group compared to 35.1% mortality in the NSG (p = 0.03).•Rescue stenting is safe, feasible and effectve and may improve outcomes in failed thrombectomies.
Journal Article
Structures of Mesocirculations Producing Tornadoes Associated with Tropical Cyclone Frances (1998)
Radar structures of one mesocyclone and one mesocirculation (the term mesocirculation refers to a class of rotating updrafts, which may or may not be as spatially and temporally large as a typical mesocyclone) that developed a total of four tornadoes in association with Tropical Cyclone (TC) Frances 1998 are presented. One tornado developed within an inner rainband near the time of landfall while three of the other tornadoes developed within an outer rainband nearly 24 hours after the landfall. Radar reflectivities of the tornadic circulations averaged upwards of 40 dBZ while Doppler radar wind components directed toward the radar averaged 11 m s-1. It is realized that although TC Frances was a minimal hurricane it spawned several tornadoes (four of which were studied) causing damage exceeding $2 million. These tornadoes were not all located close to the TC center, serving as a caution to forecasters and emergency personnel that the immediate landfalling area is not the only place to watch. While it is difficult to accurately predict the TC tornado location and time of occurrence, the degree of low-level baroclinicity seems to play an important role in tornadogenesis. Another significant finding is that the tornadoes were produced on the inward side of an inner rainband, as well as the inward side of an outer rainband. Consistent with climatology, the forward right quadrant of the TC developed the four tornadoes studied here.
Journal Article