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Jamming actuators have been proposed for many portable or wearable applications, yet the performance of these actuators will vary widely with fluidic leaks that degrade vacuum pressure and therefore maximum stiffness and stiffness over time. We investigate the power consumption and pressure in a series of leaky jamming actuators using four approaches: continuous jamming, jamming once, and re-jamming at regular intervals or if the pressure falls outside a specified range. We demonstrate the pressures and power consumptions of these approaches in a soft gripper and an active robotic elbow brace. We found that re-jamming when pressure fell below a target range reduced power consumption by more than a factor of 7.5 over continuous jamming while maintaining performance. These findings, and other efficient re-jamming approaches, will be crucial to jamming robots that can operate after damage and untethered for multiple hours. 

Extensive dampness and mold growth in buildings are some of the most common, yet overlooked indirect impacts of floods, which adversely affect human respiratory health, particularly among asthmatic individuals. There is currently a lack of understanding on interrelationships among flood characteristics and drivers, building and HVAC system properties (e.g., ventilation rates), human behaviors (e.g., time spent in homes) and vulnerability to mold growth (e.g., asthma symptoms) in the built environment, particularly in residential buildings. This project collects data in the aftermath of two recent catastrophic hurricane events - Ida and Ian - from affected residential buildings to study the relationships among flood characteristics, mold growth, building properties, human behavior and human respiratory health. Our interdisciplinary team uses survey questionnaires, laboratory experiments and machine learning modeling to answer the following scientific questions: (1) what flood characteristics and drivers, building and HVAC system properties and human behaviors cause higher levels of mold growth in residential buildings? and (2) how does living in submerged or water-damaged houses after floods affect asthma symptoms among the residents? The developed empirical database and identified relationships can be used to guide building designers and occupational health scientists to establish resilient indoor environments, provide a foundation to develop flood-induced mold growth and asthma risk models, assist public health officials and emergency managers to have a better understanding of indirect health-related impacts of floods and support the development of timely strategies for disaster management in population centers. 

As part of an NSF Research Experiences for Undergraduates Site, we have led a geologic field research program at the Aasivissuit–Nipisat Inuit Hunting Ground between Ice and Sea, which was established as a UNESCO World Heritage Site in 2018. The UNESCO site coincides with the NE-striking Ikertôq shear zone, a major component of the Paleoproterozoic Nagssugtoquidian orogeny. It also coincides with a >50 km system of pseudotachylytes – frictional melts that formed during deep earthquakes and a subject of our geologic investigations. In 2022, a team of nine students engaged in field research while immersed in the deep cultural history of the UNESCO site. The nearly 420,000 ha site preserves a 4200-year record of indigenous through colonial land use including the ruins of turf winter homes dating from the 15th to 20th centuries, the remains of summer hunting camps, burial cairns, stone hearths, and artifacts. On the western part of the UNESCO site, the focus of most of our research since 2013, the early Saqqaq culture (ca. 2200-700 BCE) inhabited a low-lying archipelago and coastal flats where the Ikertooq and Amerloq fjords empty into the Davis Strait; these sites were subsequently inhabited by newcomers to the region (Jensen et al., 2017). Most geologic and other scientific research is focused on the eastern part of the UNESCO site on or near the Greenland Ice Sheet. Here, a pilot outreach project integrates geology, climate change, and the multi-millennial history of inland hunting. The project focuses on a popular tourist destination; the 30 km road to the ice sheet east of Kangerlussuaq through the Akuliarusiarsuup Kuua glacial valley. Our work on the western coastal section of the site similarly integrates science and public outreach by providing a better understanding of bedrock geology and how ~1.8 Ga geologic structures may relate to patterns of human habitation. Our presentation will show how we continue to foster and integrate student scientific research with modern and ancient Arctic cultural awareness. 

Previous studies have described the geometry of pseudotachylyte-bearing faults in the Ikertôq shear zone (ISZ) as “paired shears.” This study found these are more complex structures formed in preexisting, wedge-shaped, imbricate damage zones. As part of an NSF REU, this project conducted outcrop-scale mapping in part of the 50-km ISZ pseudotachylyte system on Sarfannguit Island in southwestern Greenland. The pseudotachylyte system is comprised of master oblique-reverse faults concordant to strongly foliated host gneisses linked through discordant strike-slip relay faults. Within the imbricate wedges, pseudotachylytes are complexly distributed around rotated and folded gneissic blocks between stacked systems of master reverse faults. This study mapped five imbricate wedges using high resolution drone imagery in map view and hand photography on vertical outcrops. This resulted in a new geometrical three-dimensional perspective. Wedges form where foliation is platy, typically between more coherent hanging wall and footwall blocks. Preliminary calculations indicate average rotations of eight to eighteen degrees within the damage zones. Field measurements suggest the upper fault in the imbricate wedge is approximately planar, while the lower fault splays off the upper fault at a twenty to thirty degree angle, creating a concave-up cuspate geometry. Both faults have the same shear sense, with fold axes and pseudotachylyte slickenlines indicating reverse oblique offset, usually with a component of dextral shear. Initial deformation and brecciation of the blocks is interpreted as forming prior to the pseudotachylyte-forming event. 

Flow connectivity between master and relay faults in the Ikertôq shear zone demonstrates that multiple ruptures during ancient earthquakes occurred during a single seismic event. The Ikertôq shear zone (ISZ) is part of the Paleoproterozoic Nagssuqtoqidian orogeny continental collision in West Greenland that includes a > 50 km pseudotachylyte system. As part of an NSF REU, this team mapped various faults throughout a 2 km transect on high-resolution UAV images of exhumed pseudotachylyte vein systems on the western end of Sarfannguit island to investigate the kinematics of multi-fault ruptures during individual seismic events. Pseudotachylyte veins exhibit a complex rupture geometry with linked kinematics between oblique reverse master faults striking approximately 240 and steep east-west relay faults dominated by strike-slip movement. Near complete exposure of veins provide a unique opportunity to document fault linkages and the partitioning of slip, including the interconnectivity of flow patterns of melt in pseudotachylyte veins, as well as angular ladders of melt. We measured the thickness of pseudotachylyte fault veins and injection veins along transects to examine slip partitioning between multiple reverse faults and strike-slip relay faults. Melt thickness is used as a proxy for earthquake slip since the pseudotachylyte melt occurred on faults that exhibit preexisting brittle displacement. The results of preliminary calculations from energy balance equations show that typical slip on some oblique reverse master faults was on the order of a meter or less, while typical slip on some east-west relay faults was cm scale. Our data clarify that most slip occurred on oblique reverse master faults with subsidiary slip on east-west relay faults. 

High-resolution mapping of an extensive pseudotachylyte system in the Ikertôq shear zone of southwestern Greenland shows that the occurrence and style of interconnected pseudotachylyte-bearing faults are influenced by the lithology of the host rocks. The Ikertôq shear zone is a frontal structure of the Paleoproterozoic Nagssugtoquidian Orogen of which includes a 50 kilometer long pseudotachylyte system. Pseudotachylytes are vein-like rock melts that formed as a result of friction in shear zones, and are considered a proxy for paleo-earthquakes. These structures give insight into seismic behavior in the mid-upper crust. As part of an NSF REU, field observations were collected and laboratory analysis will be performed using electron microprobe, optical petrology, and scanning electron microscope (SEM) instrumentation. Our mapping of the lithologic units and boundaries along a transect of Sarfannguit Island identified lithologies varying from mafic intrusions, gabbroic pods, tonalite, felsic and intermediate gneisses, and metasedimentary rocks. Field observations such as rock unit descriptions, lithologic logs and maps show that the degree of foliation in a gniess has significant influence on the development of pseudotachylyte and fault geometry. Areas with well-foliated gneiss are characterized by a complex geometry of throughgoing pseudotachylyte-bearing faults, damage zones, imbricate wedges, and relay faults. In areas with less-foliated, thicker-banded gneiss, pseudotachylytes are less abundant and exhibit a less complex Riedel geometry. Our ongoing work will focus on gaining a better understanding of the petrology and tectonic setting of the transect. 

Meetings are routine in organizations, but their value is often questioned by the employees who must sit through them daily. The science of meetings that has emerged as of late provides necessary direction toward improving meetings, but an evaluation of the current state of the science is much needed. In this review, we examine current directions for the psychological science of workplace meetings, with a focus on applying scientific findings about the activities that occur before, during, and after meetings that facilitate success. We conclude with concrete recommendations and a checklist for promoting good meetings, as well as some thoughts on the future of the science of workplace meetings.