Accessing Passersby Proxemic Signals through a Head-Worn Camera: Opportunities and Limitations for the Blind.

The spatial behavior of passersby can be critical to blind individuals to initiate interactions, preserve personal space, or practice social distancing during a pandemic. Among other use cases, wearable cameras employing computer vision can be used to extract proxemic signals of others and thus increase access to the spatial behavior of passersby for blind people. Analyzing data collected in a study with blind (N=10) and sighted (N=40) participants, we explore: (i) visual information on approaching passersby captured by a head-worn camera; (ii) pedestrian detection algorithms for extracting proxemic signals such as passerby presence, relative position, distance, and head pose; and (iii) opportunities and limitations of using wearable cameras for helping blind people access proxemics related to nearby people. Our observations and findings provide insights into dyadic behaviors for assistive pedestrian detection and lead to implications for the design of future head-worn cameras and interactions.

Pedestrian Detection with Wearable Cameras for the Blind: A Two-way Perspective.

Blind people have limited access to information about their surroundings, which is important for ensuring one's safety, managing social interactions, and identifying approaching pedestrians. With advances in computer vision, wearable cameras can provide equitable access to such information. However, the always-on nature of these assistive technologies poses privacy concerns for parties that may get recorded. We explore this tension from both perspectives, those of sighted passersby and blind users, taking into account camera visibility, in-person versus remote experience, and extracted visual information. We conduct two studies: an online survey with MTurkers (N=206) and an in-person experience study between pairs of blind (N=10) and sighted (N=40) participants, where blind participants wear a working prototype for pedestrian detection and pass by sighted participants. Our results suggest that both of the perspectives of users and bystanders and the several factors mentioned above need to be carefully considered to mitigate potential social tensions.

A Novel Cellular Imaging Method Using Hemagglutinating Virus of Japan-Envelope (HVJ-E) Vector and Magnetic Particle Imaging.

The purpose of this study was to develop a novel cellular imaging method using the hemagglutinating virus of Japan-envelope (HVJ-E) vector and magnetic particle imaging (MPI). First, we determined the concentration of magnetic nanoparticles (MNPs) suitable for encapsulation into the HVJ-E vector (HVJ-MNPs). Colon-26 cells were labeled with HVJ-MNPs, MNPs conjugated with protamine (Pro-MNPs) or MNPs alone (Res-MNPs), and their labeling efficiencies were evaluated. Second, HVJ-MNPs, Pro-MNPs or Res-MNPs were injected directly into the tumors of tumorbearing mice and the MPI images were obtained using our MPI scanner. The temporal change of the MNPs in the tumor was quantitatively evaluated by calculating the average MPI value. In addition, the microstructures of the resected tumor tissues were observed using a transmission electron microscope (TEM). The amount of iron encapsulated into HVJ-E and the encapsulation efficiency, saturated and decreased linearly with increasing amount of added iron, respectively. The labeling efficiency of HVJ-MNPs was significantly higher than those of Res-MNPs and Pro-MNPs. In animal studies, the average MPI value in the HVJ-MNP group remained almost constant up to 14 days, whereas those in the Res-MNP and Pro-MNP groups significantly decreased at 1 day or later, compared with that at 1 hour after the injection of the agents. In the TEM studies, earlier uptake of HVJ-MNPs in the cytoplasm was observed compared with Res-MNPs and Pro-MNPs. Our results suggest that the present method is useful for cellular imaging and tracking, and that HVJ-E is effective in internalizing MNPs into cells, during cellular imaging using MPI.