The aud one out in the final battle : an Anya-centered feminist analysis of Buffy the vampire slayer

Current usability testing is often conducted via face-to-face interactions. This method can be costly, both in terms of timelines and budget. However, remote usability testing has been shown to be a viable alternative, in that performance scores have been shown to be quite similar to face-to-face methods. Although performance appears similar, remote usability testing may present challenges that threaten the validity and reliability of usability testing results. Rather than focusing on the performance of users in remote versus co-located conditions, the proposed study investigates the emotional and attitudinal responses of users engaged in software usability tests. The purpose of this study was to compare users’ anxiety and satisfaction with communication in remote and face-to-face usability tests. It was hypothesized that participants in the remote condition would exhibit a lower level of anxiety and be less satisfied with the communication method. Multiple usability tasks were administered and measures were recorded at three time intervals. Responses on the Social Anxiety Thoughts (SAT) questionnaire and the Communication Satisfaction Inventory (CSI) were collected. Although there were no significant differences between the groups in terms of anxiety and communication satisfaction, methodological limitations may have prevented the detection of differences and additional research is required to explore the strengths and weaknesses of remote usability testing

The effect of corrosion morphology on the fatigue initiation and small crack growth behavior of AA7050-T7451

Complex airframe structures often require the use of stainless steel fasteners to assemble/join aluminum substructures. A galvanic couple is created when surface coatings/sealants are breached enabling ingress of an electrolyte; this leads to corrosion damage at these inherently high stress joints. Recent US Air Force studies have demonstrated that corrosion nucleated fatigue damage represents roughly 80% of airframe fatigue damage initiation sites [1]. Despite the critical importance of this failure mode the interaction of the mechanical and electrochemical interactions for a realistic galvanic couple configuration are poorly understood. This talk will report on a collaborative effort that aims to quantify the local galvanic environments, quantitatively characterize the corrosion morphology associated with such environments, and evaluate how such morphologies influence the fatigue behavior of a modern aerospace aluminum alloy. The primary focus will be on quantitatively evaluating the macro-features, micro-features, and microstructural interactions that govern the crack formation behavior and how the relative influence of each varies with different corrosion morphologies produced using electrochemical conditions pertinent to an in-service galvanic couple. Leveraging collaborator inputs from experimental and computation analysis of the electrochemistry of a representative galvanic couple, three corrosion morphologies are considered: discrete pitting (small and large scale), a broadly corroded surface with surface recession and intergranular corrosion (IGC). Each damage morphology is induced on the SL surface of the AA7050-T7451 fatigue samples. Optical microscopy, white light interferometry, and x-ray computed tomography (XCT) are used to characterize the features of the corroded specimens. XCT is also used to identify the location of underlying constituent particles. Corroded specimens are fatigue loaded (σmax of 200 MPa, R of 0.5 and f of 20 Hz) along the L-direction in a high humidity (RH\u3e90%) that is maintained inside a plexiglass chamber. A programmed fatigue loading sequence is used mark the crack front intermittently on the fracture surface of the specimens; these fatigue-sequence induced marker bands are analyzed using the scanning electron microscope to quantify crack formation location and life ((Ni) to ≈10 μm) and crack growth rates (da/dN). Once fractography is complete the fracture surface is polished (roughly 15 μm deep) and electron back-scatter diffraction analysis is performed to enable characterization of the microstructure proximate to the crack formation site and how it intersects the growing small crack. Overall fatigue life results show a substantial and similar reduction in fatigue life due to each of the corrosion morphologies; markerband analysis demonstrates that this strong reduction is primarily due to a vast decrease in the crack formation life. Similar small crack growth rates are observed proximate to each of the corrosion features. Analysis of the macro-features of the corrosion morphology show no clear trend between crack formation sites and the damage depth, width, 3D volume, density, or proximity to surrounding damage. Furthermore the similarity in the crack formation life between different morphologies suggests that the micro-features associated with each damage type results in a similarly deleterious local condition for crack formation. The proximity of local constituent particles and the local grain orientations are evaluated to determine if there is commonality between the crack formation location and a consistent microstructure feature(s). The results and conclusion of this effort will quantitatively characterize the crack formation behavior of a relevant aerospace Al alloy in realistic conditions and leverage this data to further the mechanistic understanding of the factors governing the corrosion to fatigue crack transition. This understanding it critical to inform engineering scale prognosis strategies and provide guidance on the critical criteria for designing corrosion mitigation strategies in the context fatigue damage. References: [1] G.A. Shoales, S.A. Fawaz, M.R. Walters, in: M. Bos (Ed.) ICAF 2009 - Bridging the Gap Between Theory and Operational Practice, Springer, Rotterdam, The Netherlands, 2009, pp. 187-207

Culled Lionfish Sexual Maturity Over A Four-Year Timespan​

Lionfish are invasive in the Atlantic and the Caribbean. Like many other invasive species, they do not have any natural predators in these areas, so their population can grow unchecked. This can decrease the population of native fish species due to lionfish eating to excess. Because of their impact on native species, resource managers have incentivized lionfish hunting. Hunters were paid $6 USD for every pound of lionfish they brought in, so they possibly favored larger lionfish to increase their reward which would lead to an adaptive advantage for fish of smaller sizes. We hypothesized that the lionfish bounty program would affect the average size of lionfish and the size of females at sexual maturity, both of which should decrease. Since 2019, local fisherman brought their lionfish catch to the Tobacco Caye Marine Station to retrieve a financial bounty. Data on fish size, sex, and reproductive status was then obtained from the fish. These data were used to determine the percentage of female lionfish in each of three categories: those that were not sexually mature, those that were, and those that were in the intermediate phase of development. This data was used in conjunction with fish size to estimate the size at sexual maturity. Over the study, the size distribution of mature females appeared to decline. In 2019-2020, the smallest mature lionfish was 18-20 cm, and the average length of mature females was over 20 cm in size. By 2022, the average size of mature fish was 18.5 cm with higher percentages of mature fish in the smaller size classes than in previous years. Differential sampling effort was not accounted for in this study and would need to be addressed before drawing robust conclusions. However, the pattern suggests fishing pressure could drive earlier sexual maturation

Understanding corrosion features and alloy microstructural effects on fatigue initiation of corroded AA7050-T7451 using data science

Aluminum alloy 7050-T451 is generally used in aerospace structure due to its high strength-to-weight ratio and high toughness. Local galvanic coupling set up by wicking of electrolyte in between the stainless steel fastener used in the aircrafts and the aluminum substructure promote corrosion of AA7050-T7451. Fatigue crack initiation tend to occur on discontinuities in the aluminum alloy such as the corrosion damage created by the galvanic coupling. Previous study indicate that the individual metrics analyzed for the macro-scale (\u3e250 μm) corrosion features such as pit depth, pit density, pit volume, area of the pit mouth, do not fully correlate to the location of the fatigue crack initiation [1]. The objective of this study is to verify if there is an interaction effect on the metrics analyzed using the macro-scale corrosion damage features using data science techniques. Another objective of this study is to determine if the micro-scale (\u3c250 μm) corrosion features and the alloy microstructure play an important role in the fatigue initiation mechanism of AA7050-T7451. In order to understand the mechanism governing the fatigue crack formation, corrosion damage mimicking the galvanic coupling effect of AA7050-T7451 and SS316 are artificially created on the surface of AA7050-T7451. A small area on the LS surface of the fatigue specimens are exposed to different environmental conditions to create four different corrosion morphologies, namely, shallow and deep discrete pits, fissures and general corrosion with surface recession. These corrosion morphologies are characterized using the optical microscope, white light interferometer, scanning electron microscope and X-ray computed tomography. The specimens are subjected to fatigue loading using a special loading protocol that creates marker bands on the fracture surface. The specimens are cyclically loaded along the L-direction with σmax of 200 MPa, R ratio of 0.5 at a frequency of 20 Hz. The fatigue testing is done at 23°C and a controlled moist environment with \u3e90% relative humidity during the entire test. After fatigue testing, the fractographs of the specimens are obtained using the SEM. The marker bands from these fractographs are analyzed to calculate the crack growth rate and the fatigue initiation life to create a 10 μm crack from the initiation point are estimated. Data science approaches are employed to analyze the interaction effect of the individual metrics reported in the macro-scale corrosion feature analysis. Random forest and logistic regression modeling show that there is minimal significance between the macro-scale corrosion feature predictor variables and the fatigue crack initiation points. Even though data science indicate that these factors have less significance, these factors should not be neglected. The micro-scale corrosion features and the distribution of secondary phase particles as well as the grain character are individually analyzed and correlated to the location of the fatigue crack initiation for all the corrosion damage morphologies. Results show that these individual metrics does not fully dictate the location of the fatigue crack initiation. Future work of this study involves the use of data science techniques to understand the relationship between the micro-scale corrosion features, their possible interaction with the alloy microstructure, and the fatigue crack formation. This study will provide understanding on what governs the fatigue crack initiation and inform current micro-mechanical models to incorporate effects of pertinent parameters in predicting remaining life of corroded specimens. Reference: [1] Co NEC, Burns JT. Effects of macro-scale corrosion damage feature on fatigue crack initiation and fatigue behavior. Int J Fatigue 2017;103:234–47. doi:10.1016/j.ijfatigue.2017.05.028

Left Atrial Appendage Printing Process

The left atrial appendage senior design team aims to assist in closing off the left atrial appendage that is susceptible to coagulation due to non-valvular atrial fibrillation. Coagulation in the left atrial appendage (LAA) can be life threatening as it can lead to a stroke. Dr. Chris Porterfield performs a procedure that uses the Boston Scientific Watchman to close the appendage. He finds that sizing the Watchman properly is difficult with limited visuals from live CT scans. He proposed converting the CT scans into a 3D printed model of the left atrial appendage and left atrium so he can visually measure the opening and predict the trajectory angle of the Watchman device into the left atrial appendage. He currently has a base algorithm and procedure to convert and modify the CT scan into a .stl file, which can then be printed with standard PLA material using a 3D printer on Cal Poly’s campus. The project is limited to the printers and their material capabilities on Cal Poly’s campus. There are currently many programs that convert CT scans to printable files and this project aims to evaluate each to conclude which produces the most accurate 3D model. The procedure to create the model must also be quick to perform, repeatable and reproducible as well as easy to follow. After researching the various programs, we concluded that 3D Slicer allows us to print anatomically accurate models of the left atrium and LAA. Using this software, the user uploads CT scans obtained from the radiologist as a DICOM file. Once uploaded, the user will proceed to setting the threshold parameter to the designated values. The user will then scroll through the CT scan to identify the left atrium and LAA in one of the views. After locating the anatomies, the user will use the scissors tool to extrude out any unnecessary anatomy. Once isolated, the model will need to be hollowed out and set to the defined parameters. After a final cut is made to open the model for internal viewing, is it saved as a .stl file and sent to a 3D printing software such as Cura. From this point on, the user will refer to the printer’s manual for the printing procedure while using the parameters we listed as a guide. After the print is concluded, the user will be able to measure the opening of the LAA and determine which entry angle is most optimal. The key customer requirements we aimed to achieve were ease of use, time, production cost, shape/accuracy, repeatability and reproducibility. For ease of use, we had users go through our MPI, Training Guide and Operations Manual and had them rate between 1-10 on how clear and concise our directions were. We scaled the range so that 1 meant that our procedure was clear and concise enough to replicate while 10 meant it was near impossible to follow. We aimed to achieve an average score of less than 3. For time, we were given a timeframe of 24 hour to fully slice and print the model. Since this procedure is not officially ICD-9 billable yet, the cost of production must remain below $50 per print. Based on the sizing chart provided by Boston Scientific for the various sizes of the Watchman device, we decided that the shape/accuracy must be less than 10% variation from the CT scan, while the repeatability and reproducibility must have no statistical difference in variation from the ANOVA. After running ANOVA on the data obtained from measuring the 9 testing prints, the results showed that our slicing/printing procedure and the measurements taken for testing were adequate enough to prove the functionality of all our protocols. The results of ANOVA showed that there were no significant differences in our data except for depth reproducibility which means that our customer requirements of reproducibility and repeatability were almost met. For the ease of use requirement, Dr. Porterfield and his clinical specialist, Sarah Griess, went through our Manufacturing Process Instructions, 2 Training Guide, and Operations Manual and performed the feedback survey we provided. Based on those results, we concluded that our protocols are functional and easy to follow which is essential to producing an accurate model. To prove model accuracy, we had Dr. Porterfield size the Watchman device as he currently does and confirmed that our printed models were accurate

Localized Strain and Associated Failure of Structural Materials

Aircraft are made primarily out of strong and lightweight aluminum alloys, which are relatively low cost, easy to produce, and have allowed for several innovations in the airplane industry. Even though these alloys are highly corrosion resistant, they are susceptible to failure since airplanes experience some of the harshest fatigue and corrosion conditions. Predicting the location of crack initiation on these corroded materials could lead to preventative safety of aluminum components on an aircraft. To study the mechanisms leading to cracking, precorroded AA7050 samples were fatigue loaded to failure, virtually reconstructed form post-mortem characterizations, and modeled accordingly to obtain the micromechanical state of the material. Fatigue indicator parameters were calculated from the resulting stresses and strains. The initial corrosion front was then analyzed at the reconstructed crack plane, using a metric that identifies the most active slip planes per grain. The reconstructed data is masked over onto planes that have the same orientation as the [111] slip planes. Then, the data is analyzed quantitatively for each slip plane, looking for the highest median fatigue indicator parameter value. The slip plane on the grain closest to the crack initiation site was found to have a slip plane roughly parallel to the crack plane. On this plane, many significantly larger fatigue indicator parameter values were found, with the highest value pinpointing the region where crack initiation was experimentally observed

Enhanced corrosion protection and biocompatibility of a PLGA-silane coating on AZ31 Mg alloy for orthopaedic applications

This paper reports a multi-step procedure to fabricate a novel corrosion resistant and biocompatible PLGA-silane coating on the magnesium (Mg) alloy AZ31. The first step involves alkaline passivation followed by dip coating in a methyltriethoxysilane (MTES) and tetraethoxysilane (TEOS) mixture to produce a cross-linked siloxane coating. The second step is to impart an amine functionalization to the silane modified surface by using 3-aminopropyl-triethoxy silane (APTES) for promoting adhesion of the acid terminated poly-(lactic-co-glycolic) acid (PLGA) as a final coating step. Static contact angle measurements, Fourier transform infrared spectroscopy and scanning electron microscopy analysis confirmed the successful assembly of coatings on the AZ31 Mg alloy. Potentiodynamic polarization and impedance spectroscopy studies showed the improved initial corrosion resistance of the coated AZ31 substrate. Measurements of magnesium ion release, pH changes and hydrogen evolution showed enhanced corrosion protection of coated substrate over uncoated AZ31 alloy for 21 and 14 days respectively. The MTT assay, live-dead cells staining, DNA quantification and alkaline phosphatase activity assay were used to measure the biocompatibility, proliferation and differentiation of MC3T3-E1 osteoblast cells. Scanning electron microscopy was used to observe cell morphology and integration with the coated surface. The coated substrate showed improved cytocompatibility as compared to the uncoated AZ31 alloy surface. The application of such coatings on biodegradable Mg alloys enhanced their corrosion resistance and biocompatibility. An additional advantage is that the coating also served as a potential delivery vehicle for specific drugs and bio-active molecules releasing from an implant surface as the coatings, such as PLGA, adapt during the corrosion process, thereby enhancing bone regeneration

Staying Connected – Interactive Student Learning during the COVID Transition to Remote Learning

Background. How can we transition courses in one week, while maintaining a similar experience for students? This was probably the initial response by faculty across universities as they transitioned to remote learning, mid-semester, in response to the SARS-CoV-2 pandemic. Our approach is supported by the ICAP framework which posits that “as activities move from passive to active to constructive to interactive, students undergo different knowledge-change processes and, as a result, learning will increase.” (Chi and Wylie, 2014) Purpose/Hypothesis. How we could foster students’ interactions with course material, instructors, and their peers using collaborative technology and course activities? It was hypothesized that a collaborative environment, coupled with appropriately designed activities, would promote the interactive learning described by the ICAP framework. Design/Method. Faculty members used Microsoft Teams (Teams) and Marquette University’s Learning Management System Desire2Learn (D2L) for their courses. Each instructor developed student groups to promote peer and instructor engagement via the Teams channel function. Results. Initial results from Likert 5-point scale responses support three positive findings to this approach: Finding 1 (Instructor Engagement and Student Confidence): Students had a positive reaction to the instructor engagement (4.67 ± 0.6) and student confidence (4.07 ± 1.1). Finding 2 (Consistent Coursework): Students reported the amount of work in courses with the interactive tools was consistent (3.90 ± 1.2) with the in-class experience. Finding 3 (Collaborative Technology): Using collaborative technology (3.84 ± 1.2) enabled the students to successfully interact with their peers. The survey also provided data on opportunities for improvement for future on-line courses: Opportunity 1 (Communication): Student communication (2.57 ± 1.5) is still a barrier with collaborative technology. Opportunity 2 (On-line Format): Students also reported an overall dislike (2.44 ± 1.4) of the on-line learning format. Conclusions. The use of Teams shows that instructor engagement contributes the most to the positive experiences for confidence, consistency, and use of collaborative technology. We believe there are opportunities to develop more advantages than traditional approaches and will provide students an easier transition to industry, which already use these remote communication tools

Disrupted Maturation of the Microbiota and Metabolome among Extremely Preterm Infants with Postnatal Growth Failure

Growth failure during infancy is a major global problem that has adverse effects on long-term health and neurodevelopment. Preterm infants are disproportionately affected by growth failure and its effects. Herein we found that extremely preterm infants with postnatal growth failure have disrupted maturation of the intestinal microbiota, characterized by persistently low diversity, dominance of pathogenic bacteria within the Enterobacteriaceae family, and a paucity of strictly anaerobic taxa including Veillonella relative to infants with appropriate postnatal growth. Metabolomic profiling of infants with growth failure demonstrated elevated serum acylcarnitines, fatty acids, and other byproducts of lipolysis and fatty acid oxidation. Machine learning algorithms for normal maturation of the microbiota and metabolome among infants with appropriate growth revealed a pattern of delayed maturation of the microbiota and metabolome among infants with growth failure. Collectively, we identified novel microbial and metabolic features of growth failure in preterm infants and potentially modifiable targets for intervention

Benefits and Challenges of Multidisciplinary Project Teams: Lessons Learned for Researchers and Practitioners

Adopting a multidisciplinary research approach would enable test and evaluation professionals to more effective!y investigate the complex human performance problems faced in today\u27s technologically advanced operational domains. To illustrate the utility of this approach, we present lessons learned based on our experiences as a multi-agency, multidisciplinary team collaborating on an Army research project involving a dynamic military command and control simulation. Our goal with these lessons learned is to provide guidance to researchers and practitioners alike concerning the benefits and challenges of such collaboration. Our project team\u27s diverse members, drawn from both industry and government organizations, offer their multiple p perspectives on these issues. The final sections then summarize the challenges and benefits of multidisciplinary research