Evolution of MHC diversity in cetacean species environment: implications for the role of a pathogen

Previous studies have indicated that the evolution of diversity in the immune system genes responsible for antigen presentation in terrestrial mammals is driven by selection. However, it is not clear whether mammals in the marine environment would experience the same selective pressures as terrestrial mammals, given their different pathogen environment. The diversity and pattern of radiation of exon-2 (peptide binding region) of the DQBl locus of Class II MHC molecule was investigated in a broad range of cetacean species, including an extended sample of six focal species (three Mysticeti and three Odontoceti species). The role of natural selection and of the evolutionary history of this locus was evaluated based on phylogenetic and genetic distance analyses, in order to assess the following hypotheses: i) the marine pathogen environment presents comparable selection pressures to those of the terrestrial environment, ii) social behaviour and structure will affect pathogenic pressure and iii) populations of cetacean species with a world-wide distribution across different habitats and geographic regions are under differential selective pressure. The phylogenetic comparison of the cetacean species was consistent with the trans-species evolution pattern described for terrestrial mammals. Furthermore, high non-synonymous to synonymous substitution rates suggest that polymorphism at this locus in cetaceans is maintained by natural selection. The higher number of trans- species lineages and non-synonymous substitution rates exhibited by social species suggest that social behaviour and social structure may affect pathogenic pressure. Population differentiation according to DQBl locus reveals a contrasting pattern to that inferred by neutral markers (microsatellite DNA) supporting the hypothesis that habitat and geographic regions may place populations under differential selection pressure. The results of the present investigation suggest that the pattern of evolution of the immune response in cetaceans is similar to that in terrestrial mammal species

Elemental Water Impact Test: Phase 3 Plunge Depth of a 36-Inch Aluminum Tank Head

Spacecraft are being designed based on LS-DYNA water landing simulations. The Elemental Water Impact Test (EWIT) series was undertaken to assess the accuracy of LS-DYNA water impact simulations. Phase 3 featured a composite tank head that was tested at a range of heights to verify the ability to predict structural failure of composites. To support planning for Phase 3, a test series was conducted with an aluminum tank head dropped from heights of 2, 6, 10, and 12 feet to verify that the test article would not impact the bottom of the test pool. This report focuses on the comparisons of the measured plunge depths to LS-DYNA predictions. The results for the tank head model demonstrated the following. 1. LS-DYNA provides accurate predictions for peak accelerations. 2. LS-DYNA consistently under-predicts plunge depth. An allowance of at least 20% should be added to the LS-DYNA predictions. 3. The LS-DYNA predictions for plunge depth are relatively insensitive to the fluid-structure coupling stiffness

Sand Impact Tests of a Half-Scale Crew Module Boilerplate Test Article

Although the Orion Multi-Purpose Crew Vehicle (MPCV) is being designed primarily for water landings, a further investigation of launch abort scenarios reveals the possibility of an onshore landing at Kennedy Space Center (KSC). To gather data for correlation against simulations of beach landing impacts, a series of sand impact tests were conducted at NASA Langley Research Center (LaRC). Both vertical drop tests and swing tests with combined vertical and horizontal velocity were performed onto beds of common construction-grade sand using a geometrically scaled crew module boilerplate test article. The tests were simulated using the explicit, nonlinear, transient dynamic finite element code LS-DYNA. The material models for the sand utilized in the simulations were based on tests of sand specimens. Although the LSDYNA models provided reasonable predictions for peak accelerations, they were not always able to track the response through the duration of the impact. Further improvements to the material model used for the sand were identified based on results from the sand specimen tests

Towards Crime Prevention Using Big Data Analytics: A Literature Review with an Explorative Case Study

Since the popularization of the big data concept, it has been implemented in various areas. Contemporary literature has proved the potential of using big data in crime prevention. In this research paper, we examine research on big data being used in Crime Prevention while implementing an author-centric to a concept-centric research approach. We also present the foundation for future research by analyzing data derived from the City of Chicago. We identified the neighborhoods in Chicago that are statistically more prone to crimes and used data of the last 10 years to make our observations. We additionally provide further discussion points for future research purpose

Orion Ground Test Article Water Impact Tests: Photogrammetric Evaluation of Impact Conditions

The Ground Test Article (GTA) is an early production version of the Orion Crew Module (CM). The structural design of the Orion CM is being developed based on LS-DYNA water landing simulations. As part of the process of confirming the accuracy of LS-DYNA water landing simulations, the GTA water impact test series was conducted at NASA Langley Research Center (LaRC) to gather data for comparison with simulations. The simulation of the GTA water impact tests requires the accurate determination of the impact conditions. To accomplish this, the GTA was outfitted with an array of photogrammetry targets. The photogrammetry system utilizes images from two cameras with a specialized tracking software to determine time histories for the 3-D coordinates of each target. The impact conditions can then be determined from the target location data

Performance Evaluation of Pressure Transducers for Water Impacts

The Orion Multi-Purpose Crew Vehicle is being designed for water landings. In order to benchmark the ability of engineering tools to predict water landing loads, test programs are underway for scale model and full-scale water impacts. These test programs are predicated on the reliable measurement of impact pressure histories. Tests have been performed with a variety of pressure transducers from various manufacturers. Both piezoelectric and piezoresistive devices have been tested. Effects such as thermal shock, pinching of the transducer head, and flushness of the transducer mounting have been studied. Data acquisition issues such as sampling rate and anti-aliasing filtering also have been studied. The response of pressure transducers have been compared side-by-side on an impulse test rig and on a 20-inch diameter hemisphere dropped into a pool of water. The results have identified a range of viable configurations for pressure measurement dependent on the objectives of the test program