University of Nebraska Omaha

About: University of Nebraska Omaha is a education organization based out in Omaha, Nebraska, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 4526 authors who have published 8905 publications receiving 213914 citations. The organization is also known as: UNO & University of Omaha.

Nonlinear Analysis of Ambulatory Activity Patterns in Community-Dwelling Older Adults

Abstract: Background. The natural ambulatory activity patterns of older adults are not well understood. User-worn monitors illuminate patterns of ambulatory activity and generate data suitable for analysis using measures derived from nonlinear dynamics. Methods. Ambulatory activity data were collected continuously from 157 community-dwelling older adults for 2 weeks. Participants were separated post hoc into groups based on the mean number of steps per day: highly active (steps ≥ 10,000), moderately active (5,000 ≤ steps < 10,000 steps), and inactive (steps <5,000 steps). Detrended fl uctuation analysis (DFA), entropy rate (ER), and approximate entropy (ApEn) were used to examine the complexity of daily time series composed of 1-minute step count values. Coeffi cient of variation was used to examine time series variability. Between-group differences for each parameter were evaluated using analysis of variance. Results. All groups displayed patterns of fl uctuating step count values containing complex temporal structure. DFA, ER, and ApEn parameter values increased monotonically and signifi cantly with increasing activity level ( p < .001). The variability of step count fl uctuations did not differ among groups. Conclusions. Highly active participants had more complex patterns of ambulatory activity than less active participants. The results supported the idea that, in addition to the volume of activity produced by an individual, patterns of ambulatory activity contain unique information that shows promise for offering insights into walking behavior associated with healthy aging.

Comparison of the theoretical and experimental band structure of poly(vinylidene fluoride) crystal

Abstract: The electronic structure and band symmetries of the ferroelectric phase of poly (vinylidene fluoride) (PVDF) are studied by using the first-principles density-functional method. Our calculated results agree well with the angle-resolved photoemission experiments. We find that the PVDF crystal has an energy gap of about 6 eV at the Γ-point. Large dispersion of the valence band is found only along the chain direction, which is consistent with the quasi–one-dimensional nature of PVDF. In particular, the band symmetries of the valence states deduced theoretically are in good agreement with experiment. Finally, further investigations on the electronic structure of poly(trifluoroethylene) (PTrFE) reveal that the replacement of -(CH2-CF2)- by -(CHF-CF2)- does not change major features of the band structure.