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.

Assessing Text Readability Using Cognitively Based Indices

Abstract: Many programs designed to compute the readability of texts are narrowly based on surface-level linguistic features and take too little account of the processes which a reader brings to the text. This study is an exploratory examination of the use of Coh-Metrix, a computational tool that measures cohesion and text difficulty at various levels of language, discourse, and conceptual analysis. It is suggested that Coh-Metrix provides an improved means of measuring English text readability for second language (L2) readers, not least because three Coh-Metrix variables, one employing lexical coreferentiality, one measuring syntactic sentence similarity, and one measuring word frequency, have correlates in psycholinguistic theory. The current study draws on the validation exercise conducted by Greenfield (1999) with Japanese EFL students, which partially replicated Bormuth's (1971) study with American students. It finds that Coh-Metrix, with its inclusion of the three variables, yields a more accurate prediction of reading difficulty than traditional readability measures. The finding indicates that linguistic variables related to cognitive reading processes contribute significandy to better readability prediction than the surface variables used in traditional formulas. Additionally, because these Coh-Metrix variables better reflect psycholinguistic factors in reading comprehension such as decoding, syntactic parsing, and meaning construction, the formula appears to be more soundly based and avoids criticism on the grounds of construct validity.

Continuous inference of psychological stress from sensory measurements collected in the natural environment

Abstract: Repeated exposures to psychological stress can lead to or worsen diseases of slow accumulation such as heart diseases and cancer. The main challenge in addressing the growing epidemic of stress is a lack of robust methods to measure a person's exposure to stress in the natural environment. Periodic self-reports collect only subjective aspects, often miss stress episodes, and impose significant burden on subjects. Physiological sensors provide objective and continuous measures of stress response, but exhibit wide between-person differences and are easily confounded by daily activities (e.g., speaking, physical movements, coffee intake, etc.). In this paper, we propose, train, and test two models for continuous prediction of stress from physiological measurements captured by unobtrusive, wearable sensors. The first model is a physiological classifier that predicts whether changes in physiology represent stress. Since the effect of stress may persist in the mind longer than its acute effect on physiology, we propose a perceived stress model to predict perception of stress. It uses the output of the physiological classifier to model the accumulation and gradual decay of stress in the mind. To account for wide between-person differences, both models self-calibrate to each subject. Both models were trained using data collected from 21 subjects in a lab study, where they were exposed to cognitive, physical, and social stressors representative of that experienced in the natural environment. Our physiological classifier achieves 90% accuracy and our perceived stress model achieves a median correlation of 0.72 with self-reported rating. We also evaluate the perceived stress model on data collected from 17 participants in a two-day field study, and find that the average rating of stress obtained from our model has a correlation of 0.71 with that obtained from periodic self-reports.

When Each One Has One: The Influences on Teaching Strategies and Student Achievement of Using Laptops in the Classroom.

Abstract: In this study, we examined the educational effects of providing fifth-, sixth-, and seventh-grade students with 24-hour access to laptop computers. Specifically we examined the impact of laptops on classroom activities, and on student use of technology and their writing and problem-solving skills. Participating teachers received computer integration training using the iNtegrating Technology for inQuiry (NTeQ) model to develop problem-based lessons that engage students in critically examining authentic issues, and strengthen research and writing skills. A matched treatment-control group design was employed, in which classes taught at the same grade levels in five participating schools served as the laptop (1 computer per student) and control (5+ computers per class) contexts. Participants included students, teachers, and parents from the two groups. Although systematic observations revealed relatively few differences in teaching methods between laptop and control classrooms, laptop students used computers more frequently, extensively, and independently. Writing assessment results showed substantial and significant advantages for laptop over control students, with six of eight effect sizes exceeding +0.80. Results also showed significant advantages for the laptop group on five of the seven components of the problem-solving task.

Deacetylation of Chitosan: Material Characterization and in vitro Evaluation via Albumin Adsorption and Pre-Osteoblastic Cell Cultures

Abstract: Degree of deacetylation (DDA) and molecular weight (MW) of chitosans are important to their physical and biological properties. In this study, two chitosans, HS (DDA = 73.3%) and AT (DDA = 76.8%), were deacetylated with 45% sodium hydroxide under nitrogen atmosphere at 80 °C or 90 °C for up to 120 min, to obtain two series of chitosans. The polymers produced were characterized for MW by gel permeation chromatography, DDA by titration and UV-vis methods, and crystallinity, hydrophilicity and thermal stability by X-ray diffraction, water contact angle and differential scanning calorimetry respectively. Films, made by solution casting in dilute acetic acid at ambient conditions, were evaluated for biological activity by albumin adsorption and the attachment and growth of a pre-osteoblast cell line. Chitosans with between 80–93% DDA’s (based on titration) were reproducibly obtained. Even though deacetylation under nitrogen was supposed to limit chain degradation during decetylation, MW decreased (by maximum of 37.4% of HS and 63.0% for AT) with increasing deacetylation reaction time and temperature. Crystallinity and decomposition temperature increased and water contact angles decreased with processing to increase DDA. Significantly less albumin was absorbed on films made with 93% DDA chitosans as compared with the original materials and the AT chitosans absorbed less than the HS chitosans. The cells on higher DDA chitosan films grew faster than those on lower DDA films. In conclusion, processing conditions increased DDA and influenced physicochemical and biological properties. However, additional studies are needed to unambiguously determine the influence of DDA or MW on in vitro and in vivo performance of chitosan materials for bone/implant applications.

Alcohol demand, delayed reward discounting, and craving in relation to drinking and alcohol use disorders.

Abstract: A behavioral economic approach to alcohol use disorders (AUDs) emphasizes both individual and environmental determinants of alcohol use. The current study examined individual differences in alcohol demand (i.e., motivation for alcohol under escalating conditions of price) and delayed reward discounting (i.e., preference for immediate small rewards compared to delayed larger rewards) in 61 heavy drinkers (62% with an AUD). In addition, based on theoretical accounts that emphasize the role of craving in reward valuation and preferences for immediate rewards, craving for alcohol was also examined in relation to these behavioral economic variables and the alcohol-related variables. Intensity of alcohol demand and delayed reward discounting were significantly associated with AUD symptoms, but not with quantitative measures of alcohol use, and were also moderately correlated with each other. Likewise, craving was significantly associated with AUD symptoms, but not with alcohol use, and was also significantly correlated with both intensity of demand and delayed reward discounting. These findings further emphasize the relevance of behavioral economic indices of motivation to AUDs and the potential importance of craving for alcohol in this relationship.