University of Memphis

About: University of Memphis is a education organization based out in Memphis, Tennessee, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 7710 authors who have published 20082 publications receiving 611618 citations. The organization is also known as: U of M.

cStress: towards a gold standard for continuous stress assessment in the mobile environment

Abstract: Recent advances in mobile health have produced several new models for inferring stress from wearable sensors. But, the lack of a gold standard is a major hurdle in making clinical use of continuous stress measurements derived from wearable sensors. In this paper, we present a stress model (called cStress) that has been carefully developed with attention to every step of computational modeling including data collection, screening, cleaning, filtering, feature computation, normalization, and model training. More importantly, cStress was trained using data collected from a rigorous lab study with 21 participants and validated on two independently collected data sets --- in a lab study on 26 participants and in a week-long field study with 20 participants. In testing, the model obtains a recall of 89% and a false positive rate of 5% on lab data. On field data, the model is able to predict each instantaneous self-report with an accuracy of 72%.

An Introduction to Latent Variable Mixture Modeling (Part 2): Longitudinal Latent Class Growth Analysis and Growth Mixture Models

Abstract: Objective — Pediatric psychologists are often interested in finding patterns in heterogeneous longitudinal data. Latent Variable Mixture Modeling is an emerging statistical approach that models such heterogeneity by classifying individuals into unobserved groupings (latent classes) with similar (more homogenous) patterns. The purpose of the second of a two article set is to offer a nontechnical introduction to longitudinal latent variable mixture modeling. Methods — 3 latent variable approaches to modeling longitudinal data are reviewed and distinguished. Results — Step-by-step pediatric psychology examples of latent growth curve modeling, latent class growth analysis, and growth mixture modeling are provided using the Early Childhood Longitudinal Study-Kindergarten Class of 1998–99 data file. Conclusions — Latent variable mixture modeling is a technique that is useful to pediatric psychologists who wish to find groupings of individuals who share similar longitudinal data patterns to determine the extent to which these patterns may relate to variables of interest.

Injectable bone cements for use in vertebroplasty and kyphoplasty: State‐of‐the‐art review

Abstract: Vertebroplasty (VP) and kyphoplasty (KP) are minimally invasive surgical procedures that have recently been introduced for the medical management of osteoporosis-induced vertebral compression fractures. The aim of VP is to stabilize the fractured vertebral body, while the goals of KP are to stabilize the fractured vertebral body and to restore its height to as near its prefracture level as possible. Both procedures involve injection of the setting dough of an injectable bone cement (IBC) into the fractured vertebral body, thereby highlighting the indispensable role that the IBC plays. Although there is a very large literature on IBCs, no detailed critical review of it has been published. Such a review is the subject of the present work, which is in seven parts. The review opens with a succinct introduction to VP and KP. The topics covered in the parts that follow are: (1) a listing of the 18 most desirable properties of an IBC (e.g., easy injectability, high radiopacity, and a resorption rate that is neither too high nor too low); (2) descriptions of the four classes of IBCs (calcium phosphates, acrylic bone cements, calcium sulfates, and composites); (3) concerns that have been raised with regard to the use of IBCs (such as the potential for thermal necrosis of tissue at the peri-augmentation site, when an acrylic bone cement is used); (4) explicative summaries of the main findings of literature studies on the influence of nine factors (such as powder particle size, powder-to-liquid ratio, and the method used to mix the powder and the liquid) on the values of various properties of IBCs; (5) explicative summaries of the main findings of literature studies on five fundamental matters, such as the aging mechanism of the powder, the thermokinetics of a setting dough, and the influence of the type of IBC used on various ex vivo biomechanical performance measures of VP- and KP-augmented vertebral bodies; and (6) descriptions of topics in six areas for future research, such as the determination of an overall index of the fatigue performance of an IBC and the development of internationally recognized standardized testing protocols to employ when a synthetic cancellous bone void model is used in the rapid in vitro screening of IBCs. The review ends with a summary of the most salient points and observations made.