Iowa State University

About: Iowa State University is a education organization based out in Ames, Iowa, United States. It is known for research contribution in the topics: Population & Gene. The organization has 50151 authors who have published 107716 publications receiving 3355909 citations. The organization is also known as: Iowa State University of Science and Technology & Iowa State College.

A review of feedforward control approaches in nanopositioning for high-speed spm

Abstract: Control can enable high-bandwidth nanopositioning needed to increase the operating speed of scanning probe microscopes (SPMs). High-speed SPMs can substantially impact the throughput of a wide range of emerging nanosciences and nanotechnologies. In particular, inversion-based control can find the feedforward input needed to account for the positioning dynamics and, thus, achieve the required precision and bandwidth. This article reviews inversion-based feedforward approaches used for high-speed SPMs such as optimal inversion that accounts for model uncertainty and inversion-based iterative control for repetitive applications. The article establishes connections to other existing methods such as zero-phase-error-tracking feedforward and robust feedforward. Additionally the article reviews the use of feedforward in emerging applications such as SPM-based nanoscale combinatorial-science studies, image-based control for subnanometer-scale studies, and imaging of large soft biosamples with SPMs.

Alginate Production by Pseudomonas putida Creates a Hydrated Microenvironment and Contributes to Biofilm Architecture and Stress Tolerance under Water-Limiting Conditions

Abstract: Biofilms exist in a variety of habitats that are routinely or periodically not saturated with water, and residents must integrate cues on water abundance (matric stress) or osmolarity (solute stress) into lifestyle strategies. Here we examine this hypothesis by assessing the extent to which alginate production by Pseudomonas putida strain mt-2 and by other fluorescent pseudomonads occurs in response to water limitations and how the presence of alginate in turn influences biofilm development and stress tolerance. Total exopolysaccharide (EPS) and alginate production increased with increasing matric, but not solute, stress severity, and alginate was a significant component, but not the major component, of EPS. Alginate influenced biofilm architecture, resulting in biofilms that were taller, covered less surface area, and had a thicker EPS layer at the air interface than those formed by an mt-2 algD mutant under water-limiting conditions, properties that could contribute to less evaporative water loss. We examined this possibility and show that alginate reduces the extent of water loss from biofilm residents by using a biosensor to quantify the water potential of individual cells and by measuring the extent of dehydration-mediated changes in fatty acid composition following a matric or solute stress shock. Alginate deficiency decreased survival of desiccation not only by P. putida but also by Pseudomonas aeruginosa PAO1 and Pseudomonas syringae pv. syringae B728a. Our findings suggest that in response to water-limiting conditions, pseudomonads produce alginate, which influences biofilm development and EPS physiochemical properties. Collectively these responses may facilitate the maintenance of a hydrated microenvironment, protecting residents from desiccation stress and increasing survival.

Coming of Age Too Early: Pubertal Influences on Girls' Vulnerability to Psychological Distress

Abstract: This 4-year longitudinal study investigates 3 hypothesized effects of the pubertal transition on the psychological distress of adolescent girls (N = ca. 200): early maturation, the impact of heterosexual versus same-sex friends, and prepubertal vulnerabilities, such as early emotional distress and father hostility. Building on Caspi and Moffitt's study of girls' delinquency, this study found that early maturing girls experienced significantly higher levels of psychological distress compared to their on-time and late maturing age-mates. In line with prior studies of girls' delinquency (Caspi, Lynam, Moffitt, & Silva, 1993; Magnusson, 1988), early maturing girls also experienced higher levels of distress at the tenth grade as reported by fathers, mothers, and adolescents when they were associated with mixed- rather than same-sex friends during the seventh through ninth grades. Finally, early maturing girls were more vulnerable to prior psychological problems, deviant peer pressures, and fathers' hostile feelings when compared to on-time and late maturing peers.

Attachment, self-compassion, empathy, and subjective well-being among college students and community adults

Abstract: Research on subjective well-being suggests that it is only partly a function of environmental circumstances. There may be a personality characteristic or a resilient disposition toward experiencing high levels of well-being even in unfavorable circumstances. Adult attachment may contribute to this resilient disposition. This study examined whether the association between attachment anxiety and subjective well-being was mediated by Neff's (2003a, 2003b) concept of self-compassion. It also examined empathy toward others as a mediator in the association between attachment avoidance and subjective well-being. In Study 1, 195 college students completed self-report surveys. In Study 2, 136 community adults provided a cross-validation of the results. As expected, across these 2 samples, findings suggested that self-compassion mediated the association between attachment anxiety and subjective well-being, and emotional empathy toward others mediated the association between attachment avoidance and subjective well-being.