Seismic deployments in the Alaska subduction zone provide dense sampling of the seismic wavefield that constrains thermal structure and subduction geometry. We measure
Most robots for minimally invasive surgery (MIS) are large, bulky devices which mimic the paradigm of manual MIS by manipulating long, rigid instruments from outside the body [1]. Some of these incorporate “wristed” instruments to place some local dexterity at or near the tool tip [2]. In contrast, a small number of MIS robot designs place all of the degrees of freedom inside the patient’s body in order to increase the local dexterity [3].
more » « less- Award ID(s):
- 1659777
- NSF-PAR ID:
- 10230174
- Date Published:
- Journal Name:
- Frontiers in Biomedical Devices
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
more » « less
Abstract P andS attenuation from pairwise amplitude and phase spectral ratios for teleseismic body waves at 206 stations from regional and short‐term arrays. Parallel teleseismic travel‐time measurements provide information on seismic velocities at the same scale. These data show consistently low attenuation over the forearc of subduction systems and high attenuation over the arc and backarc, similar to local‐earthquake attenuation studies but at 10× lower frequencies. The pattern is seen both across the area of normal Pacific subduction in Cook Inlet, and across the Wrangell Volcanic Field where subduction has been debated. These observations confirm subduction‐dominated thermal regime beneath the latter. Travel times show evidence for subducting lithosphere much deeper than seismicity, while attenuation measurements appear mostly reflective of mantle temperature less than 150 km deep, depths where the mantle is closest to its solidus and where subduction‐related melting may take place. Travel times show strong delays over thick sedimentary basins. Attenuation signals show no evidence of absorption by basins, although some basins show signals anomalously rich in high‐frequency energy, with consequent negative apparent attenuation. Outside of basins, these data are consistent with mantle attenuation in the upper 220 km that is quantitatively similar to observations from surface waves and local‐earthquake body waves. Differences betweenP andS attenuation suggest primarily shear‐modulus relaxation. Overall the attenuation measurements show consistent, coherent subduction‐related structure, complementary to travel times. -
more » « less
Abstract Objectives Capuchin monkeys (
Cebus spp. andSapajus spp.) routinely extract food resources that are embedded in protective matrices. Features such as relative brain size, manual dexterity, and— in the case ofSapajus spp.— a robust feeding system are considered adaptations for accessing embedded foods. Compared with adults, juvenile capuchins exhibit reduced food processing efficiency when processing embedded foods. Although this reduced efficiency has been attributed to inexperience or lack of strength when processing embedded foods, little is known about how food material properties (FMPs) relate to age‐related changes in feeding efficiency.Materials and methods We used data collected from three groups of
Sapajus libidinosus to test relationships between feeding efficiency and FMP variation when processing embedded and nonembedded foods. Feeding efficiency was defined in three ways: (i) duration, (ii) frequency, and (iii) variation in sequence of food processing behaviors.Results We found limited support for an effect of FMPs and age on feeding sequence durations or on processing behavior frequency. Number of unique behavioral patterns was negatively correlated with age. Embedded foods elicited longer durations, higher behavioral frequencies and more unique behaviors compared to nonembedded foods.
Discussion Results indicate FMP variation impedes some measures of juvenile food processing efficiency. Foods with high stress‐limited indices reduced some measures of processing efficiency in juveniles. These data are consistent with prior studies of juvenile capuchin feeding competency when exploiting embedded foods and suggest skill development may be a relatively more important constraint for overall juvenile feeding efficiency than body size or strength.
-
Concentric tube robots (CTRs) have drawn significant research attention over the years, particularly due to their applications in minimally invasive surgery (MIS). Indeed, their small size, flexibility, and high dexterity enable several potential benefits for MIS. Research has led to an increasing number of discoveries and scientific breakthroughs in CTR design, fabrication, control, and applications. Numerous prototypes have emerged from different research groups, each with their own design and specifications. This survey paper provides an overview of the state-of-the-art of the mechatronics aspects of CTRs, including approaches for the design and fabrication of the tubes, actuation unit, and end effector. In addition to the various hardware and associated fabrication methods, we propose to the research community, a unifying way of classifying CTRs based on their actuation unit architecture, as well as a set of specification details for evaluation of future CTR prototypes. Finally, we also aim to highlight the current advancements, challenges, and perspectives of CTR design and fabrication.more » « less
-
null (Ed.)People come in different shapes and sizes, but most will perform similarly well if asked to complete a task requiring fine manual dexterity – such as holding a pen or picking up a single grape. How can different individuals, with different sized hands and muscles, produce such similar movements? One explanation is that an individual’s brain and nervous system become precisely tuned to mechanics of the body’s muscles and skeleton. An alternative explanation is that brain and nervous system use a more “robust” control policy that can compensate for differences in the body by relying on feedback from the senses to guide the movements. To distinguish between these two explanations, Uyanik et al. turned to weakly electric freshwater fish known as glass knifefish. These fish seek refuge within root systems, reed grass and among other objects in the water. They swim backwards and forwards to stay hidden despite constantly changing currents. Each fish shuttles back and forth by moving a long ribbon-like fin on the underside of its body. Uyanik et al. measured the movements of the ribbon fin under controlled conditions in the laboratory, and then used the data to create computer models of the brain and body of each fish. The models of each fish’s brain and body were quite different. To study how the brain interacts with the body, Uyanik et al. then conducted experiments reminiscent of those described in the story of Frankenstein and transplanted the brain from each computer model into the body of different model fish. These “brain swaps” had almost no effect on the model’s simulated swimming behavior. Instead, these “Frankenfish” used sensory feedback to compensate for any mismatch between their brain and body. This suggests that, for some behaviors, an animal’s brain does not need to be precisely tuned to the specific characteristics of its body. Instead, robust control of movement relies on many seemingly redundant systems that provide sensory feedback. This has implications for the field of robotics. It further suggests that when designing robots, engineers should prioritize enabling the robots to use sensory feedback to cope with unexpected events, a well-known idea in control engineering.more » « less
-
Robotic-assisted minimally invasive surgery (MIS) has enabled procedures with increased precision and dexterity, but surgical robots are still open loop and require surgeons to work with a tele-operation console providing only limited visual feedback. In this setting, mechanical failures, software faults, or human errors might lead to adverse events resulting in patient complications or fatalities. We argue that impending adverse events could be detected and mitigated by applying context-specific safety constraints on the motions of the robot. We present a context-aware safety monitoring system which segments a surgical task into subtasks using kinematics data and monitors safety constraints specific to each subtask. To test our hypothesis about context specificity of safety constraints, we analyze recorded demonstrations of dry-lab surgical tasks collected from the JIGSAWS database as well as from experiments we conducted on a Raven II surgical robot. Analysis of the trajectory data shows that each subtask of a given surgical procedure has consistent safety constraints across multiple demonstrations by different subjects. Our preliminary results show that violations of these safety constraints lead to unsafe events, and there is often sufficient time between the constraint violation and the safety-critical event to allow for a corrective action.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1115/dmd2018-6821
