Using a Head-Mounted Video Camera to Understand Social Worlds and Experiences

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Tennessee tornado frequency, vulnerability, and relation to a large-scale climate variability

This work explores the climatologies of isolated tornadoes and tornado outbreaks across the state of Tennessee, a state that in some years experiences more tornadoes than states in the heart of Tornado Alley. Part one assesses tornado frequency characteristics and fatality statistics within 100 km of three major Tennessee cities (Nashville, Memphis, and Knoxville) between 1950 and 2013. Nashville reported the most tornadoes, (426) but Memphis reported the most fatalities. Knoxville and Nashville tornadoes occurred on fewer days, while Memphis tornadoes were spread across more tornado days. Spring was the most active season for tornadoes, but Memphis still experienced approximately 25% of its total tornadoes in the winter, a season prone to nocturnal tornadoes. There was no statistically significant difference between the seasonality of tornadoes for each of the cities, which is surprising given the longitudinal expanse of the state. Regional-scale analyses of this type provide insight on how tornado risk and vulnerability may vary considerably across a single state. Part two analyzes tornado outbreak characteristics (1980–2014) from a climatological perspective and assesses how a large-scale climate oscillation may affect tornado and tornado-outbreak frequencies across Tennessee. Results indicate that 72.5% of all tornadoes in Tennessee occur in outbreaks, when an outbreak is subjectively defined as any 24-hour period with four or more tornadoes within the state. Winter, defined as Dec/Jan/Feb, had the second-highest tornado-outbreak frequency. This provides a possible explanation for the high frequency of tornado-related fatalities in Tennessee, as the winter is a time of reduced daylight and is when nocturnal tornadoes, which are twice as likely to kill, are most prevalent. The Multivariate ENSO Index (MEI) was investigated using generalized linear models with a Quasi-Poisson distribution to determine if a relationship existed between tornado activity and a large-scale climate oscillation. Results indicate that above (below) average values of MEI, or El Niño (La Niña) events, are related to times of decreased (increased) tornado activity across Tennessee, and are supported by meteorological considerations. Offering future estimations of tornado activity on a seasonal or monthly scale can aid in reducing susceptibility to these dangerous events

Formation of plasma around a small meteoroid: simulation and theory

High‐power large‐aperture radars detect meteors by reflecting radio waves off dense plasma that surrounds a hypersonic meteoroid as it ablates in the Earth's atmosphere. If the plasma density profile around the meteoroid is known, the plasma's radar cross section can be used to estimate meteoroid properties such as mass, density, and composition. This paper presents head echo plasma density distributions obtained via two numerical simulations of a small ablating meteoroid and compares the results to an analytical solution found in Dimant and Oppenheim (2017a, https://doi.org/10.1002/2017JA023960, 2017b, https://doi.org/10.1002/2017JA023963). The first simulation allows ablated meteoroid particles to experience only a single collision to match an assumption in the analytical solution, while the second is a more realistic simulation by allowing multiple collisions. The simulation and analytical results exhibit similar plasma density distributions. At distances much less than λT, the average distance an ablated particle travels from the meteoroid before a collision with an atmospheric particle, the plasma density falls off as 1/R, where R is the distance from the meteoroid center. At distances substantially greater than λT, the plasma density profile has an angular dependence, falling off as 1/R^2 directly behind the meteoroid, 1/R^3 in a plane perpendicular to the meteoroid's path that contains the meteoroid center, and exp - 1.5(/λ)2/3/ in front of the meteoroid. When used for calculating meteoroid masses, this new plasma density model can give masses that are orders of magnitude different than masses calculated from a spherically symmetric Gaussian distribution, which has been used to calculate masses in the past.This work was supported by NSF grants AGS-1244842 and AGS-1056042. This work used the Extreme Science and Engineering Discovery Environment (XSEDE), which is supported by National Science Foundation grant ACI-1548562. The authors acknowledge the Texas Advanced Computing Center (TACC) at The University of Texas at Austin for providing HPC resources that have contributed to the research results reported within this paper; URL: http://www.tacc.utexas.edu. Simulation-produced data are archived at TACC and available upon request. (AGS-1244842 - NSF; AGS-1056042 - NSF; ACI-1548562 - National Science Foundation)First author draf

Feasibility Test of the MedaCube

Poor adherence is a significant barrier to achieve better patient outcomes. Rates of non-adherence approach 40% resulting in 10% of all emergency department visits and 23% of admissions into skilled nursing facilities. Many factors contribute to medication non-adherence including psychological and memory disorders, aging and pill burden. The MedaCube is a medication management system intended to help solve unintentional medication non-adherence. The device is designed to dispense scheduled and as-needed oral medications. The MedaCube provides audio and visual prompts alerting subjects to administer their medications. Caregivers receive notification of missed doses, late doses and refill requests. The null hypothesis is that use of the MedaCube results in no difference in medication adherence when compared with six month prior adherence in individual subjects