Can real-time visual feedback during gait retraining reduce metabolic demand for individuals with transtibial amputation?

The metabolic demand of walking generally increases following lower extremity amputation. This study used real-time visual feedback to modify biomechanical factors linked to an elevated metabolic demand of walking in individuals with transtibial amputation. Eight persons with unilateral, traumatic transtibial amputation and 8 uninjured controls participated. Two separate bouts of real-time visual feedback were provided during a single session of gait retraining to reduce 1) center of mass sway and 2) thigh muscle activation magnitudes and duration. Baseline and post-intervention data were collected. Metabolic rate, heart rate, frontal plane center of mass sway, quadriceps and hamstrings muscle activity, and co-contraction indices were evaluated during steady state walking at a standardized speed. Visual feedback successfully decreased center of mass sway 12% (p = 0.006) and quadriceps activity 12% (p = 0.041); however, thigh muscle co-contraction indices were unchanged. Neither condition significantly affected metabolic rate during walking and heart rate increased with center-of-mass feedback. Metabolic rate, center of mass sway, and integrated quadriceps muscle activity were all not significantly different from controls. Attempts to modify gait to decrease metabolic demand may actually adversely increase the physiological effort of walking in individuals with lower extremity amputation who are young, active and approximate metabolic rates of able-bodied adults

Encoderless Gimbal Calibration of Dynamic Multi-Camera Clusters

Dynamic Camera Clusters (DCCs) are multi-camera systems where one or more cameras are mounted on actuated mechanisms such as a gimbal. Existing methods for DCC calibration rely on joint angle measurements to resolve the time-varying transformation between the dynamic and static camera. This information is usually provided by motor encoders, however, joint angle measurements are not always readily available on off-the-shelf mechanisms. In this paper, we present an encoderless approach for DCC calibration which simultaneously estimates the kinematic parameters of the transformation chain as well as the unknown joint angles. We also demonstrate the integration of an encoderless gimbal mechanism with a state-of-the art VIO algorithm, and show the extensions required in order to perform simultaneous online estimation of the joint angles and vehicle localization state. The proposed calibration approach is validated both in simulation and on a physical DCC composed of a 2-DOF gimbal mounted on a UAV. Finally, we show the experimental results of the calibrated mechanism integrated into the OKVIS VIO package, and demonstrate successful online joint angle estimation while maintaining localization accuracy that is comparable to a standard static multi-camera configuration.Comment: ICRA 201

Tyrosine-Based Signals Regulate the Assembly of Daple⋅PARD3 Complex at Cell-Cell Junctions.

Polarized distribution of organelles and molecules inside a cell is vital for a range of cellular processes and its loss is frequently encountered in disease. Polarization during planar cell migration is a special condition in which cellular orientation is triggered by cell-cell contact. We demonstrate that the protein Daple (CCDC88C) is a component of cell junctions in epithelial cells which serves like a cellular "compass" for establishing and maintaining contact-triggered planar polarity. Furthermore, these processes may be mediated through interaction with the polarity regulator PARD3. This interaction, mediated by Daple's PDZ-binding motif (PBM) and the third PDZ domain of PARD3, is fine-tuned by tyrosine phosphorylation on Daple's PBM by receptor and non-receptor tyrosine kinases, such as Src. Hypophosphorylation strengthens the interaction, whereas hyperphosphorylation disrupts it, thereby revealing an unexpected role of Daple as a platform for signal integration and gradient sensing for tyrosine-based signals within the planar cell polarity pathway

“Run Forrest Run!”: Measuring the Impact of App-Enabled Performance and Social Feedback on Running Performance

Exercise tracking apps offer a novel and powerful channel to deliver behavioral interventions at a massive scale. As thousands of fitness tracking solutions emerge, the lack of systematic research quantifying their effectiveness on exercise outcomes becomes more prominent. Drawing on the motivation literature, this paper elucidates the effects of app-enabled motivation on fitness improvement. Specifically, this study examines the two most common forms of feedback available to users of exercise tracking apps, namely performance feedback and social feedback. The results of our field experiment reveal strong evidence that performance feedback and social feedback motivate fitness improvement. Furthermore, whereas the effect of social feedback diminishes over time, the effect of performance feedback remains resilient. There theoretical and practical implications of the findings are discussed

Effects of Speaker-Identity Cueing on Listening Effort During Speech-in-Noise

The brain is an organ that performs a variety of intricate functions. Specifically, the brain has an amazing ability to recover the complexities of a speech signal within a mixture of sounds. The process of extracting the speech signal from background noise, however, is not necessarily straightforward or easy. Previous studies have developed the concept of “listening effort” as an umbrella term to include all cognitive demand listeners confront to understand speech. From a clinical standpoint, this term suggests that accuracy measurements alone are not sufficient, and a supplementary assessment of how hard a client must try in order to understand speech (especially when the speech is degraded due to background noise) must be conducted. Current research emphasis is on the post-speech-time compensatory processes in recovering speech cues. However, in this study, we claim pre-speech-time attentional processes also create a source of listening effort. To support this idea, we measured the cortical, behavioral, and pupillary responses of 19 normal-hearing participants to SiN conditions when speaker-identity cues were provided before speech. We found that such speaker-identity cues significantly increased alpha oscillations in fronto-temporal cortex during post-cue pre-target time. Cortical evoked responses to target speech exhibited significantly greater amplitude in the cued condition, indicating speaker-identity cues enhance attentional processes. Grand-mean pupil dilation was larger in the cued condition, albeit the difference was not significant. The speaker-identity cues did not alter accuracy significantly, which guaranteed that our comparisons on pupil and EEG responses were not affected by the ratio of correct trials in across-trial averages. Combining these results, we claim that listening effort is not always an inherently bad, fatiguing process, but rather, includes top-down brain mechanisms that help listeners better attend to a target speech signal in background noise

Do They Tweet Differently? A Cross-Cultural Group Study of Twitter Use on Mobile Communication Devices

Culture is one of the classic and most widely studied topics in the field of technology. People of different cultural backgrounds interpret, consume, and disseminate technology differently. One conspicuous aspect of culture is communication. The expression, conversational patterns, and contextual nuances of different languages make communication a distinct cultural experience. Culture influences how communication functions between different people in different social contexts. It is also an underlying feature of encoded messages; a knowledge of the sender’s culture helps to discern his or her intention. Communication technology is also susceptible to the influence of culture. The mobile and social aspects of technology add another dimension to the communication process. Twitter, a leading social medium run on a mobile communication device, is a good example. This empirical study examines the use of Twitter in users with two distinctly different cultural ideologies: individualism (characteristic of the U.S.A.) and collectivism (common in Korea). Participants in both countries took part in a four-man group decision-making experiment. The groups were given decision tasks to complete within a timed period. The study yielded the following results: 1) the Korean participants tweeted significantly more often than the American participants; 2) the Korean participants initiated significantly more new tweets than the American participants; 3) the Korean participants sent significantly more friendly tweets than the American participants; 4) the American participants expressed disagreement significantly more often than the Korean participants; and 5) the Korean participants exhibited a significantly higher level of group cohesiveness than the American participants. These results shed light on the cultural applications of this new, emerging technology which is becoming essential to personal and business information sharing and communication of people of different cultures all over the world. Data analysis, discussion, and implications are provided