Nasal Bone

Per observation, a person was observed for a 30-min period in daycare, airport, bar, church, classroom, food court, museum, public library, university library, and sporting event environments. Subjects were not explicitly aware of being observed and were chosen at random in the location by the observer. If it was clear that the observer was noticed or if the person being observed left the location before the 30-min observation period had ended, this entire observation was excluded from the study. The observer made a best estimate of the gender and age of the participant (male/female), and there was no interaction between the observer and the participants.
In total, 263 people were observed: 99 adult males, 100 adult females, 32 male children, and 32 female children. Each observation was categorized as eating (i.e., person was eating food) or non-eating (i.e., person was not eating food, regardless of drinking activities). Contacts with the nose, mouth, or eyes, along with other areas, including cheek, forehead, temples, hair, ears, and neck, were recorded by hand where each new contact was listed in chronological order on the activity observation form.
Only areas of the nose, mouth, and eyes thought to potentially lead to infection were counted towards nose, mouth, and eye contact frequencies. Specifically, nose contacts were defined as contact with the inner or outer nose (nostril area, excluding nasal bone or bridge of the nose) surfaces and under the nose. Mouth contacts were defined as contact with the lips, teeth, or inner mouth surfaces. Contact with the eyes included contact with the corner of the eye, the eyelid, conjunctiva or an eye rub. Contacts with the head included any of these contacts or contacts with the cheek, forehead, temples, hair, chin, ears, or neck. Contacts defined as “other” excluded the mouth, eyes, or nose and included contacts with the cheek, temples, hair, chin, ears, or neck. Although some contacts, such as contact to the outside of the nose, may not directly result in a dose or exposure for all cases, due to challenges in the angle of the observer, we assumed any contact with these surfaces pertaining to the nose, mouth, or eye surfaces could result in a dose. Each recorded touch began when contact was made and finished at the first lift of the hand from the contacted facial surface.
The time (hour and minute) for each contact was recorded. Contacts with parts of the head other than the mouth, eyes, or nose were grouped together in the analysis as “other.” The University of Arizona Office for Human Research Protections determined human subjects review was not required (Protocol Number: 1911145109). One observer conducted all the observations in 2001 and has since passed away. Observation forms were translated to a digital spreadsheet format by one researcher. This researcher and another researcher separately chose entries from the digital spreadsheet at random and checked agreement with the original observation forms. Descriptive statistics of contact frequencies and transitional probabilities for contact sequences are reported here to inform exposure estimation and risk assessment.

Animals (n = 10) were initially anesthetized using a ketamine/xylazine cocktail (85 mg/kg ketamine, and 10 mg/kg xylazine), with supplemental ketamine given ∼ every 40-60 minutes as needed to maintain a stable anesthetic level, and also to maintain anesthesia at stage III characterized by predominantly slow oscillations^{62 (link)};0.05 mg/kg atropine was also given separately to help decrease secretions and counteract cardiac and respiratory depression. After anesthesia and craniotomy was performed, epidural stimulation electrodes were implanted (using skull-screws embedded in the skull), in the configuration noted in Fig 5. The ground screw for this and all other stimulation experiments was implanted over the contralateral nasal bone, suggesting current flow would likely go through cortex and associated pathways in an anterior-medial direction from the site of stimulation. These screws were connected to a Multi-Channel Systems Stimulus Generator (MCS STG4000 series) to deliver direct-current stimulation. In 3 animals, ∼2mm tungsten wire was placed on epidural surface in the craniotomy well instead of using skull screws to deliver the electrical stimulation. 32-ch multi-electrode arrays were implanted into Layer 5 of motor cortex (1200 – 1500 μm deep). Single-unit and LFP activity was recorded for 1 hour to ensure stability of recordings and minimize drift during stimulation experiment. Then, we recorded a base-line period of neural activity (∼ 15 minutes), followed by neural activity during direct-current stimulation (typically using 10 – 100 μA currents, applied for 1 - 5 minutes).