University of Nebraska–Lincoln

About: University of Nebraska–Lincoln is a education organization based out in Lincoln, Nebraska, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 28059 authors who have published 61544 publications receiving 2139104 citations. The organization is also known as: Nebraska & UNL.

First-order transition in confined water between high-density liquid and low-density amorphous phases.

Abstract: Supercooled water and amorphous ice have a rich metastable phase behaviour. In addition to transitions between high- and low-density amorphous solids1,2, and between high- and low-density liquids3,4,5,6,7,8, a fragile-to-strong liquid transition has recently been proposed9,10, and supported by evidence from the behaviour of deeply supercooled bilayer water confined in hydrophilic slit pores11. Here we report evidence from molecular dynamics simulations for another type of first-order phase transition—a liquid-to-bilayer amorphous transition—above the freezing temperature of bulk water at atmospheric pressure. This transition occurs only when water is confined in a hydrophobic slit pore12,13,14 with a width of less than one nanometre. On cooling, the confined water, which has an imperfect random hydrogen-bonded network, transforms into a bilayer amorphous phase with a perfect network (owing to the formation of various hydrogen-bonded polygons) but no long-range order. The transition shares some characteristics with those observed in tetrahedrally coordinated substances such as liquid silicon15,16, liquid carbon17 and liquid phosphorus18.

How interpretive qualitative research extends mixed methods research.

Abstract: Recently several authors have criticized mixed methods research because it relegates qualitative research to secondary or auxiliary status, it expresses this status through experimental trials that privilege quantitative research, and it fails to employ critical, interpretive approaches to qualitative research. This paper is a response to this position, and we draw on leading qualitative and feminist researchers who advance the importance of mixed methods research. We also cite empirical mixed methods articles that give priority to qualitative research, as well as mixed methods studies that use critical interpretive approaches. Our overall argument is that qualitative research can enhance mixed methods research, and we give specific examples as illustrations.

Parent and teacher ratings of attention-deficit/hyperactivity disorder symptoms: Factor structure and normative data.

Abstract: Changes in the diagnostic criteria for attention-deficit/hyperactivity disorder (ADHD) have necessitated the creation of new measures for clinical assessment. The factor structure of a parent rating scale containing the 18 symptoms of ADHD was examined in this study. Factor analyses and assessment of differences in ADHD ratings across sex, age, and ethnic group were conducted using a sample of 4666 participants ranging in age from 4 to 20 years old who attended kindergarten through 12th grade in 22 school districts across the United States. Two factors (Inattention and Hyperactivity-Impulsivity) were derived and normative data for a nationally representative sample are presented. A higher frequency of ADHD symptoms was found for boys, younger children, and African-American participants. Potential uses of this scale in clinical practice and research are discussed.