Effects of Head Formation and Heat Treatment on the Mechanical Properties of Connecting Rod Bolts

Oliver Racing Parts (ORP; Charlevoix, Michigan) is looking to optimize their manufacturing process for high-strength connecting rod bolts. A high yield strength is desired for the bolts because deformation would result in catastrophic engine failure. The bolts were made of H11, a chromium hot-work tool steel; and MLX17, a precipitation hardenable stainless steel. Tensile testing was performed to determine the tensile and yield strengths of the bolts. Fracture surfaces were imaged via scanning electron microscopy to characterize the failure modes. To observe the effects of bolt heading on microstructure and bolt strength, two batches of MLX17 were prepared; one batch being headed then aged (Group A); the other batch being headed, solution annealed, and then aged (Group B). These bolts were compared to H11 bolts to determine their viability for use, with the results being in the order of highest to lowest yield strength: H11 (272 ksi), MLX17 Treatment B (250 ksi), and MLX17 Treatment A (235 ksi). In the order of highest to lowest tensile strength: H11 (300 ksi), MLX17 Group B (255 ksi), MLX17 Group A (238 ksi). It is suggested that the bolt heading process is causing some overaging in the MLX17 samples, shown by the increase in strength when strain and aging from the heading process are undone through heat treatment. H11 bolts were the strongest tested. Recommendations are to not replace H11 bolts with MLX17 due to a decrease in strength

Estimating age composition for multiple years when there are gaps in the ageing data: the case of western Atlantic bluefin tuna

Age–length key (ALK) methods generally perform well when length samples and age samples are representative of the underlying population. It is unclear how well these methods perform when lengths are representative but age samples are sparse (i.e. age samples are small or missing in many years, and some length groups do not have any age observations). With western Atlantic bluefin tuna, the available age data are sparse and have been, for the most part, collected opportunistically. We evaluated two methods capable of accommodating sparse age data: a novel hybrid ALK (combining forward ALKs and cohort slicing) and the combined forward-inverse ALK. Our goal was to determine if the methods performed better than cohort slicing, which has traditionally been used to obtain catch-at-age for Atlantic bluefin tuna, given the data limitations outlined above. Simulation results indicated that the combined forward-inverse ALK performed much better than the other methods. When applied to western Atlantic bluefin tuna data, the combined forward-inverse ALK approach was able to track cohorts and identified an inconsistency in the ageing of some samples

Characterization and standardization of the Atlantic albacore French pelagic trawl fishery

We compiled and analysed logbook data from the French trawl albacore fishery covering the period 1991–2015. The dataset comprised catch and effort data for the French fleet operating in the Bay of Biscay and Celtic Sea, as well as spatiotemporal and gear characteristics. Generalized linear modelling was used to model spatial, seasonal, environmental, and gear covariates of fleet CPUE rates. A long-term index of relative abundance is provided that can be integrated into the stock assessment of North Atlantic albacore. The analysis revealed higher albacore CPUE associated with relatively low sea surface temperature and distinct seasonal effects. The derived abundance trend for the French trawl fishery agreed with the estimated time series of stock abundance from recent assessments

Pain symptomology, functional impact, and treatment of people with Neurofibromatosis type 1

Introduction: Neurofibromatosis type 1 (NF1) is a neurogenetic disorder affecting 1 in 3000 people worldwide, where individuals are prone to develop benign and malignant tumors. In addition, many people with NF1 complain of pain that limits their daily functioning. Due to the complexity of the disorder, there are few options for treating pain symptoms besides surgery and medications. Moreover, the spectrum of pain symptomatology and treatment, as well as the mechanisms underlying NF1-associated pain, has been understudied. Methodology: To address this knowledge gap, we conducted a survey of 255 adults with NF1, leveraging the Washington University NF1 Patient Registry Initiative (NPRI) database. Demographic and pain data were collected using a Qualtrics survey. Results: All participants had at least one surgical procedure, with 55% reporting having at least one surgery within the last year and 17% being currently prescribed opioid medication. A positive relationship was shown ( Conclusion: The current study demonstrates that individuals with NF1 report a higher incidence of pain severity and interference than observed in NF1 previous studies, with pain symptoms not localized to any specific region of the body. The consideration for alternative treatments and careful monitoring of current treatments that are more conservative or have less potential adverse side effects may improve pain management and reduce the risk of developing medication dependence

Testing robustness of CPUE standardization and inclusion of environmental variables with simulated longline catch datasets

Environmental variability changes the distribution, migratory patterns, and susceptibility to various fishing gears for highly migratory marine fish. These changes become especially problematic when they affect the indices of abundance (such as those based on catch-per-unit-effort: CPUE) used to assess the status of fish stocks. The use of simulated CPUE data sets with known values of underlying population trends has been recommended by ICCAT (International Commission for the Conservation of Atlantic Tunas) to test the robustness of CPUE standardization methods. A longline CPUE data simulator was developed to meet this objective and simulate fisheries data from a population with distinct habitat preferences. The simulation was used to test several statistical hypotheses regarding best practices for index standardization aimed at accurate estimation of population trends. Effort data from the US pelagic longline fleet was paired with a volume-weighted habitat suitability model for blue marlin (Makaira nigricans) to derive a simulated time series of blue marlin catch and effort from 1986 to 2015 with four different underlying population trends. The simulated CPUE data were provided to stock assessment scientists to determine if the underlying population abundance trend could accurately be detected with different methods of CPUE standardization that did or did not incorporate environmental data. While the analysts’ approach to the data and the modeling structure differed, the underlying population trends were captured, some more successfully than others. In general, the inclusion of environmental and habitat variables aided the standardization process. However, differences in approaches highlight the importance of how explanatory variables are categorized and the criteria for including those variables. A set of lessons learned from this study was developed as recommendations for best practices for CPUE standardization.FCT IF/00253/2014info:eu-repo/semantics/publishedVersio

Identifying trade-offs and reference points in support of ecosystem approaches to managing Gulf of Mexico menhaden

Gulf menhaden (Brevoortia patronus) support the largest fishery by yield in the Gulf of Mexico (GoM) and are a key forage species for many marine predators. While menhaden stock assessments indicated that overfishing was not likely to have occurred in the past, concerns have been raised regarding the possible effects of menhaden fishing on their predators. In this study, we used a US Gulfwide Ecopath with Ecosim (EwE) model to explore the predicted effects of increased menhaden harvest on the GoM ecosystem and focused our analyses on Gulf menhaden predators. Key menhaden predators identified included king mackerel (Scomberomorus cavalla), Spanish mackerel (Scomberomorus maculatus), sea trout (Cynoscion spp.), red drum (Sciaenops ocellatus), and pelagic coastal piscivores [e.g., bluefish (Pomatomus saltatrix)]. As expected, these predators exhibited reduced biomass in response to increased Gulf menhaden harvest, with a predicted 11% decrease in predator biomass at simulated fishing levels near historical highs. Our results indicate strong relationships between the effects of menhaden fishing and the predator fishing mortality for king mackerel and intermediate relationships for Spanish mackerel, blacktip shark (Carcharhinus limbatus), red drum, large coastal sharks, and pelagic coastal piscivores. Biomass of predator groups such as demersal coastal invertebrate feeders [e.g., drums and croakers (Sciaenidae)] are more affected by menhaden harvest (through trophodynamics interactions and bycatch removal) compared to the isolated effect of their fishing mortality. For almost all the groups examined in the trade-off analysis, with the exception of sea trout, current biomass (2016) was higher than their target biomass representing 75% of their biomass at maximum sustainable yield. In comparison to the time series of fishing mortality rates estimated by the most recent Gulf menhaden stock assessment, the mean ecological reference point (ERP) of 0.862 was exceeded in all but 1 year from 1977 to 2007; however, neither the target nor threshold upper ERP value has been exceeded since 2008. The observed Gulf menhaden landings from 2003 to the present were generally within the range of the projected equilibrium landings (i.e., within confidence intervals) at both the ERP target and threshold values except for three recent years

Evaluating Atlantic bluefin tuna harvest strategies that use conventional genetic tagging data

An individual tagging model was implemented within the spatial, seasonal, multi-stock, multi-fleet operating models of the peer-reviewed Management Strategy Evaluation (MSE) framework for Atlantic bluefin tuna to evaluate the benefits of a harvest strategy that utilizes conventional gene tagging. A multi-year Brownie estimator was developed to test the accuracy and precision of exploitation rate estimates arising from gene tagging programs with various scenarios for spatial release distribution, release numbers and fishery exploitation rates. Harvest strategies that used the Brownie estimator were tested to evaluate yield and resource conservation performance relative to idealized management using perfect information. For the eastern stock, releasing 1,000 fish throughout the Atlantic and genotyping 27% of all landed fish at an estimated cost of US$2M was sufficient to obtain estimates of exploitation rate with a coefficient of variation of 20$2.5M. Harvest strategies using the gene tagging data provided expected yield and resource conservation performance that was not substantially lower than a harvest strategy assuming using perfect information regarding vulnerable biomass. Reducing the number of releases most strongly affected the worst-case ‘lower-tail’ outcomes for West area yield and eastern stock biomass. Conventional gene tagging harvest strategies offer a promising basis for calculating management advice for Atlantic bluefin tuna that may be cheaper, simpler, and more robust than the current conventional stock assessment paradigm

KRAS(G12D) and TP53(R167H) Cooperate to Induce Pancreatic Ductal Adenocarcinoma in Sus scrofa Pigs

Although survival has improved in recent years, the prognosis of patients with advanced pancreatic ductal adenocarcinoma (PDAC) remains poor. Despite substantial differences in anatomy, physiology, genetics, and metabolism, the overwhelming majority of preclinical testing relies on transgenic mice. Hence, while mice have allowed for tremendous advances in cancer biology, they have been a poor predictor of drug performance/toxicity in the clinic. Given the greater similarity of sus scrofa pigs to humans, we engineered transgenic sus scrofa expressing a LSL-KRASG12D-TP53R167H cassette. By applying Adeno-Cre to pancreatic duct cells in vitro, cells self-immortalized and established tumors in immunocompromised mice. When Adeno-Cre was administered to the main pancreatic duct in vivo, pigs developed extensive PDAC at the injection site hallmarked by excessive proliferation and desmoplastic stroma. This serves as the first large animal model of pancreatic carcinogenesis, and may allow for insight into new avenues of translational research not before possible in rodents

Spectrophotometric Modeling and Mapping of (101955) Bennu

Using hyperspectral data collected by OVIRS, the visible and infrared spectrometer on board the Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) spacecraft, we modeled the global average spectrophotometric properties of the carbonaceous asteroid (101955) Bennu and mapped their variations. We restricted our analysis to 0.4–2.5 μm to avoid the wavelengths where thermal emission from the asteroid dominates (>2.5 μm). Bennu has global photometric properties typical of dark asteroids; we found a geometric albedo of 0.046 ± 0.007 and a linear phase slope of 0.024 ± 0.007 mag deg−1 at 0.55 μm. The average spectral slope of Bennu’s normal albedo is −0.0030 μm−1, and the phase-reddening parameter is 4.3 × 10−4 μm−1 deg−1, both over the spectral range of 0.5–2.0 μm. We produced normal albedo maps and phase slope maps at all spectral channels, from which we derived spectral slope and phase-reddening maps. Correlation analysis suggests that phase slope variations on Bennu are likely due to photometric roughness variation. A correlation between photometric and thermal roughness is evident, implying that the roughness of Bennu is self-similar on scales from tens of microns to meters. Our analysis reveals latitudinal trends in the spectral color slope and phase reddening on Bennu. The equatorial region appears to be redder than the global average, and the spectral slope decreases toward higher latitudes. Phase reddening on Bennu is relatively weak in the equatorial region and shows an asymmetry between the northern and southern hemispheres. We attributed the latitudinal trend to the geophysical conditions on Bennu that result in a global pattern of mass flow toward the equator