Weep Hole Inspection for Radial Fatigue Cracks by Circumferential Creeping Waves

Weep holes are drilled through risers in wet-wing structures in order to permit remanent fuel to be evenly distributed during flight. Unfortunately, they can become the sites from which fatigue cracks tend to originate. Figure 1 shows the schematic diagram of weep holes cut into the vertical risers of an airplane wing used as a fuel tank. The cracks have been found to grow in either the upward or downward or both directions. These fatigue cracks initially grow in a radial direction perpendicular to the wing skin surface. Downward growing cracks can be easily detected using a 45-degree shear wave transducer. The main objective of this study was the development of an ultrasonic detection technique for the less accessible upward growing cracks. The blowup in Figure 1 shows the geometrical configuration of such an upward growing fatigue crack

3D Printed Aircraft

This project is to design, build, and test a 3D-printable aircraft. The goal is to create a final design that will be able to fly for the longest duration possible, around 20 seconds. To determine the correct preliminary design and manufacturing process for a 3D printed RC aircraft, an analysis of multiple design options and manufacturing materials was performed. This allowed for a variety of choices for aircraft type, airfoil design, structure, among other topics to be narrowed down to the most promising option. It has been found that the aircraft will follow a design similar to industry motor-gliders, with a lightweight wing design and airfoil common to glider models. With regards to the manufacturability, the aircraft will be printed using a Fused Deposition Modeling (FDM) printer in carbon fiber polypropylene to optimize weight to strength ratio. These findings are critical to understanding the large scale applications of 3D printing in the aerospace industry, with a particular focus on fixed wing aircraft

CPAs and Big 4 office audit quality

Both accounting firms and regulators recognize the importance of human capital in the audit function, yet we know little about whether and how the level of professionally qual-ified human capital varies across offices of an audit firm and whether it is associated with audit quality. In this paper, we examine the association between office professionally qualified human capital and audit quality. Using hand-collected data on Big 4 audit firm office CPA levels from 30 U.S. cities, we find that offices with relatively more professionally qual-ified human capital deliver higher quality audits, with this benefit being more pronounced for audits performed during busy season than for non-busy season audits. The results underscore the importance of the availability of professionally qualified human capital in an audit office to the office’s audit quality. Our finding of CPA levels being an office-level audit quality indicator will potentially help the PCAOB in their ongoing Audit Quality Indicator (AQI) project, whose goal is to assist audit firms, clients, and investors in measur-ing audit quality. Furthermore, the results lend credibility toward the CPA designation, which helps justify the AICPA’s, NASBA’s, and state Accountancy Boards’ regulatory roles of admitting and licensing qualified candidates

Macrophage PPARg , a Lipid Activated Transcription Factor Controls the Growth Factor GDF3 and Skeletal Muscle Regeneration

Tissue regenerationrequiresinflammatoryand repar- atory activity of macrophages. Macrophages detect and eliminate the damaged tissue and subsequently promote regeneration. This dichotomy requires the switch of effector functions of macrophages coordi- nated with other cell types inside the injured tissue.\ud The gene regulatory events supporting the sensory and effector functions of macrophages involved in tissue repair are not well understood. Here we show that the lipid activated transcription factor, PPAR g , is required for proper skeletal muscle regeneration, acting in repair macrophages. PPAR g controls the expression of the transforming growth factor- b (TGF- b ) family member, GDF3, which in turn regu- lates the restoration of skeletal muscle integrity by promoting muscle progenitor cell fusion. This work establishes PPAR g as a required metabolic sensor and transcriptional regulator of repair macrophages. Moreover, this work also establishes GDF3 as a secreted extrinsic effector protein acting on myo- blasts and serving as an exclusively macrophage- derived regeneration factor in tissue repair

Development of the legitimacy threshold scale

A consensus in the literature supports the premise that legitimacy attainment facilitates favorable judgments from key stakeholders regarding the acceptability, appropriateness and worthiness of entrepreneurs and their efforts in emerging ventures. However, although legitimacy attainment is a milestone that emerging ventures strive to reach, as researchers we do not yet have a measure that examines whether a firm is operating pre- versus post-legitimacy. Accordingly, we develop the legitimacy threshold scale (LTS) that will facilitate the assessment of activities performed pre- and post-legitimacy in emerging ventures

Insights on carbapenem-resistant Acinetobacter baumannii : phenotypic characterization of relevant isolates

Acinetobacter baumannii (A. baumannii) is an important nosocomial pathogen, which may be a causative agent in a wide-range of human pathologies. Carbapenems are usually considered the last safe and effective choice of drugs for the treatment of Gram-negative infections. The emergence of carbapenem-resistant A. baumannii (CRAB) is a critical public health issue as they leave clinicians with limited therapeutic options. In this study, phenotypic methods were used to characterize sixty-two (n = 62) A. baumannii isolates, which were included based on their suspected non-susceptibility to meropenem. Minimum inhibitory concentrations (MICs) of meropenem, levofloxacin, gentamicin, sulfamethoxazole/trimethoprim, tigecycline were determined using E-tests, while colistin MICs were determined using broth microdilution. The isolates were subjected to the modified Hodge test (MHT), the modified carbapenem-inactivation method (mCIM) and the imipenem/EDTA combined disk test (CDT). Efflux pump overexpression was studied using agar plates containing phenylalanine-arginine β-naphthylamide (PAβN). Assessment of biofilm-formation was carried out using the crystal violet tube-adherence method. 64.5% of the strains showed meropenem MICs in the resistant range (>8 mg/L), resistance rates were similarly high to the other tested antibiotics. The MHT and mCIM assay were positive in 79.0% and 67.7% of cases, respectively; the presence of an MBL was suggested for 29.0% of isolates. Efflux-pump overexpression was seen in 12.9% of isolates. 54.8% of the isolates were characterized as strong biofilm-producers. Microbiology laboratories have an important role in differentiating the distinct mechanisms by which these pathogens develop the CRAB phenotype, as plasmid-borne carbapenemases are significant from the standpoint of public health microbiology

Same Coverage, Less Bloat: Accelerating Binary-only Fuzzing with Coverage-preserving Coverage-guided Tracing

Coverage-guided fuzzing's aggressive, high-volume testing has helped reveal tens of thousands of software security flaws. While executing billions of test cases mandates fast code coverage tracing, the nature of binary-only targets leads to reduced tracing performance. A recent advancement in binary fuzzing performance is Coverage-guided Tracing (CGT), which brings orders-of-magnitude gains in throughput by restricting the expense of coverage tracing to only when new coverage is guaranteed. Unfortunately, CGT suits only a basic block coverage granularity -- yet most fuzzers require finer-grain coverage metrics: edge coverage and hit counts. It is this limitation which prohibits nearly all of today's state-of-the-art fuzzers from attaining the performance benefits of CGT. This paper tackles the challenges of adapting CGT to fuzzing's most ubiquitous coverage metrics. We introduce and implement a suite of enhancements that expand CGT's introspection to fuzzing's most common code coverage metrics, while maintaining its orders-of-magnitude speedup over conventional always-on coverage tracing. We evaluate their trade-offs with respect to fuzzing performance and effectiveness across 12 diverse real-world binaries (8 open- and 4 closed-source). On average, our coverage-preserving CGT attains near-identical speed to the present block-coverage-only CGT, UnTracer; and outperforms leading binary- and source-level coverage tracers QEMU, Dyninst, RetroWrite, and AFL-Clang by 2-24x, finding more bugs in less time.Comment: CCS '21: Proceedings of the 2021 ACM SIGSAC Conference on Computer and Communications Securit

Environmental Studies Senior Seminar 2003: Invasive Species

The class of 2003 was the first to graduate with Environmental Studies degrees from the University of Richmond. At that time, the Senior Seminar was a two-semester class, ENVR 391 and 392. It was taught by a pair of professors; Stephen P. Nash, Journalism, and Peter D. Smallwood, Biology. Students chose the problem of invasive species for their focus. With tremendous help from the staff of the Virginia chapter of The Nature Conservancy, and from Delegate James Dillard, the students proposed legislation to help Virginia deal with this environmental problem. Students wrote opinion pieces for local papers throughout Virginia in support of the bill, and spoke to several organizations (e.g., Virginia Master Gardeners Club, Virginia Master Naturalists). Students and faculty lobbied members of the Virginia General Assembly for this bill, eventually securing its passage. It was signed into law by Governor Mark Warner in April 2003. After the bill was passed, the class spent the rest of the semester researching volunteer programs for early detection of invasive species. One of the more pernicious problems of invasive species is that once they have spread far enough, eradication becomes extremely difficult. Thus the best hope for controlling invasive species is to detect them as early as possible. Each student found a particular volunteer program, investigated its strengths and weaknesses, and wrote up their findings in a manual, meant as a resource for land managers in Virginia and other states. As of this writing, the manual is still available through the National Invasive Species Council (here) Included in this folder are: Virginia Code Chapter 433 (the text of the act as signed into law by Governor Warner) Virginia Invasive Species 2003 (a poster describing the work to pass the bill) Early Detectives – Invasive Species 2003 (the manual describing volunteer programs for early detection of invasive species)