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Earthquake-related failure modes for embankment dams are commonly evaluated through numerical simulations using finite element or finite difference approaches. This is especially true for liquefaction triggering or cyclic softening of fine-grained materials where advanced constitutive models are used to capture the dynamic response of the dam and the nonlinear behavior of the soil. Both liquefaction and cyclic softening can lead to significant strength loss, which can lead to large deformations within the dam, but these numerical tools often cannot capture these large deformations due to excessive mesh distortion and subsequent numerical errors. This leads to significant uncertainties in estimating potential crest settlement, which is often a critical value for risk assessments of dams. Hybrid numerical methods like the material point method (MPM) offer a promising alternative to model large deformations, but their application to dams is still limited and relatively little validation has been done on using MPM for post-earthquake stability analyses. This study focuses on applying MPM simulations to evaluate the post-earthquake stability of a hypothetical embankment dam and to examine potential deformations of a flowslide that occurred in Palu, Indonesia in 2018. The MPM program Anura3D is used for the analyses with modifications to allow for assigning residual strengths. The results from the Palu flowslide are compared with observations from the field to show that the MPM analyses are able to capture the extent of the slide, but underpredict the measured displacements in the central portion of the flowslide. The analyses for the embankment dam are compared with post-earthquake stability results from finite difference analyses using FLAC. The MPM analyses are able to capture the full deformation of the flowslide, while the FLAC analyses are halted due to excessive mesh deformation. These results demonstrate the potential of MPM to be used as a complement to existing numerical tools for evaluating the seismic response of dams, but additional work is needed to validate this approach using case histories with both large and small deformations. 

Our knowledge of the biodiversity of Asia and Australasia continues to expand with more focused studies on systematics of various groups and their biogeography. Historically, fluctuating sea levels and cyclic connection and separation of now-disjunct landmasses have been invoked to explain the accumulation of biodiversity via species pump mechanisms. However, recent research has shown that geological shifts of the mainland and species dispersal events may be better explanations of the biodiversity in these regions. We investigate these processes using the poorly studied and geographically widespread Mud Snakes (Serpentes: Homalopsidae) using a target capture approach of ~4,800 nuclear loci from fresh tissues and supplemental mitochondrial data from formalin tissues from museum specimens. We use these datasets to reconstruct the first resolved phylogeny of the group, identify their biogeographic origins, and test hypotheses regarding the roles of sea-level change and habitat selection on their diversification. Divergence dating and ancestral range estimation yielded support for an Oligocene origin and diversification from mainland Southeast Asia and Sundaland in the rear-fanged group ~20 million years ago, followed by eastward and westward dispersal. GeoHiSSE models indicate that niche expansion of ancestral, rear-fanged lineages into aquatic environments did not impact their diversification rates. Our results highlight that Pleistocene sea-level changes and habitat specificity did not primarily lead to the extant species richness of Homalopsidae and that, alternatively, geological shifts in mainland Southeast Asia may have been a major driver of diversity in this group. We also emphasize the importance of using fresh and degraded tissues, and both nuclear and mitochondrial DNA, for filling knowledge gaps in poorly known but highly diverse and conceptually important groups. Here, Homalopsidae represents a non-traditional but effective model study system for understanding transitions between terrestrial, marine, and freshwater environments. 

The authors present the design and implementation of an exploratory virtual learning environment that assists children with autism (ASD) in learning science, technology, engineering, and mathematics (STEM) skills along with improving social-emotional and communication skills. The primary contribution of this exploratory research is how educational research informs technological advances in triggering a virtual AI companion (AIC) for children in need of social-emotional and communication skills development. The AIC adapts to students’ varying levels of needed support. This project began by using puppetry control (human-in-the-loop) of the AIC, assisting students with ASD in learning basic coding, practicing their social skills with the AIC, and attaining emotional recognition and regulation skills for effective communication and learning. The student is given the challenge to program a robot, Dash™, to move in a square. Based on observed behaviors, the puppeteer controls the virtual agent’s actions to support the student in coding the robot. The virtual agent’s actions that inform the development of the AIC include speech, facial expressions, gestures, respiration, and heart color changes coded to indicate emotional state. The paper provides exploratory findings of the first 2 years of this 5-year scaling-up research study. The outcomes discussed align with a common approach of research design used for students with disabilities, called single case study research. This type of design does not involve random control trial research; instead, the student acts as her or his own control subject. Students with ASD have substantial individual differences in their social skill deficits, behaviors, communications, and learning needs, which vary greatly from the norm and from other individuals identified with this disability. Therefore, findings are reported as changes within subjects instead of across subjects. While these exploratory observations serve as a basis for longer term research on a larger population, this paper focuses less on student learning and more on evolving technology in AIC and supporting students with ASD in STEM environments. 

Tissue engineering has been largely confined to academic research institutions with limited success in commercial settings. To help address this issue, more work is needed to develop new automated manufacturing processes for tissue-related technologies. In this article, we describe the automation of the funnel-guide, an additive manufacturing method that uses living tissue rings as building units to form bio-tubes. We developed a method based on 96-well plates and a modified off-the-shelf liquid-handling robot to retrieve, perform real-time quality control, and transfer tissue rings to the funnel-guide. Cells seeded into 96-well plates containing specially designed agarose micromolds self-assembled and formed ring-shaped microtissues that could be retrieved using a liquid-handling robot. We characterized the effects of time, cell type, and mold geometry on the morphology of the ring-shaped microtissues to inform optimal use of the building parts. We programmed and modified an off-the-shelf liquid-handling robot to retrieve ring-shaped microtissues from the 96-well plates, and we fabricated a custom illuminated pipette to visualize each ring-shaped microtissue prior to deposit in the funnel guide. Imaging at the liquid-air interface presented challenges that were overcome by controlling lighting conditions and liquid curvature. Based on these images, we incorporated into our workflow a real-time quality control step based on visual inspection and morphological criteria to assess each ring prior to use. We used this system to fabricate bio-tubes of endothelial cells with luminal alignment. 

ABSTRACT Composite nanostructured foams consisting of a metallic shell deposited on a polymeric core were formed by plating copper via electroless deposition on electrospun polycaprolactone (PCL) fiber mats. The final structure consisted of 1000-nm scale PCL fibers coated with 100s of nm of copper, leading to final core-shell thicknesses on the order of 1000-3000 nm. The resulting open cell, core-shell foams had relative densities between 4 and 15 %. By controlling the composition of the adjuncts in the plating bath, particularly the composition of formaldehyde, the relative thickness of copper coating as the fiber diameter could be controlled. As-spun PCL mats had a nominal compressive modulus on the order of 0.1 MPa; adding a uniform metallic shell increased the modulus up to 2 MPa for sub-10 % relative density foams. A computational materials science analysis using density functional theory was used to explore the effects pre-treatment with Pd may have on the density of nuclei formed during electroless plating.