Ultrasonic wave propagation in heterogenous media

The non-destructive testing of austenitic steel welds using ultrasound is of vital importance for assessing safety critical structures such as those found in the nuclear industry. The internal geometry of these welds is heterogeneous and highly scattering and this makes it dicult to detect and characterise any defects within them. To help overcome these diculties the use of ultrasound transducer arrays and the associated Full Matrix Capture is becoming more widespread. There is a need therefore to develop post-processing algorithms that best utilise the data from such devices. This paper considers the use of a time-frequency domain method known as the Decomposition of the Time Reversal Operator (DORT) method. To develop this method and to demonstrate its ecacy in tackling this problem a series of simulated data sets are used. The simulated data is generated using a finite element method (PZFLEX) with the heterogeneous internal microstructure of the weld being given by previous Electron Backscatter Diraction measurements. A range of artificial flaws are then inserted into this geometry. By varying the flaw size and type a comparison is conducted between the DORT method and the Total Focusing Method (TFM) and their relative ability to perform flaw detection assessed. Importantly, however, the DORT method relies on a Singular Value Decomposition in time and frequency space and this spectral information contains information about the flaw size and shape

Exploring the Influence of Object Similarity and Desirability on Children's Ownership Identification and Preferences in Autism and Typical Development

This study investigated how ownership identification accuracy and object preferences in children with autism spectrum disorder (ASD) are influenced by visual distinctiveness and relative desirability. Unlike typically developing (TD) children matched on receptive language (M age equivalents: 58.8–59.9 months), children with ASD had difficulty identifying another person’s property when object discriminability was low and identifying their own relatively undesirable objects. Children with ASD identified novel objects designated to them with no greater accuracy than objects designated to others, and associating objects with the self did not bias their preferences. We propose that, due to differences in development of the psychological self, ownership does not increase the attentional or preferential salience of objects for children with ASD

AN EXPLORATION OF THE EFFECT OF KNEE-TO-FEET JUMPS ON PERFORMANCE

The purpose of this study was to test the effect of knee-to-feet jump training on power and vertical jump height. Twenty-one varsity athletes from power-emphasized sports were paired and randomly placed in the control or experimental group. All subjects completed pre- and post-tests of vertical jump height, knee-to-feet jump height, and 2 repetition maximum hang clean. The experimental group completed a 6 week program of knee-tofeet jumps. There was no significant difference in vertical jump height or hang clean weight from pre- to post-test; however, the experimental group significantly improved in knee-to-feet jump height. There was a positive correlation between knee-to-feet jump and vertical jump height indicating knee-to-feet jumps are a potentially useful tool worth further pursuit

The dependence of Pb distribution in brain cells on the interactions of astroglia and neurons

Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to [email protected], referencing the URI of the item.Includes bibliographical references: leaves 24-25.Lead (Pb) is a ubiquitous environmental contaminant which has been linked to neurobehavioral deficits, primarily in young children. A current hypothesis for Pb distribution among brain cells is that astroglia, which are interposed between the blood capillaries and neurons, protect neurons by Pb uptake and storage. This property of astroglia is thought to develop with age, and is not present in very young animals. The purpose of this study was to test three hypotheses: that maturation of neuronal cells affects their Pb accumulation, that soluble factors secreted into astroglial environment alters their Pb accumulation, and that astroglia preferentially sequester Pb over neurons. In an initial experiment, SY5Y human neuroblastoma cells were exposed to medium containing low levels of Pb and Neuronal Growth Factor-b (NGF-b), a soluble factor secreted by astroglia which induces cell maturation. In a second experiment, astroglia were exposed to endothelial-, astroglia-, and neuronal-conditioned media containing low levels of Pb. In a final experiment, astroglia and neuronal cells were exposed to Pb in a bicameral co-culture system, in which cell types were physically separated but shared a common pool of medium. Graphite Furnace Atomic Absorption Spectroscopy (AAS) was used to determine Pb amounts, which were expressed per number of cells. Results showedneuronal cell maturation, induced by NGF-b, lead to a decrease in Pb uptake. Furthermore, soluble factors secreted by neuronal cells caused a significant increase in the amount of Pb uptake by cultured astroglia, as determined in both conditioned medium and co-culture experiments. Our findings support the conclusion that astroglial accumulation of Pb increases with exposure to influencing factors from neuronal cells and that neuronal cell accumulation decreases with maturation. These findings are in agreement with the Lead sink hypothesis

ISU ADVANCE Collaborative Transformation Project: Rounds 1 and 2 - Focal Department Synthesis Report

This report summarizes research from the Iowa State University ADVANCE Collaborative Transformation (CT) Project. The results discussed here are based on intensive research conducted within six Science, Technology, Engineering and Mathematics (STEM) departments at ISU during 2006-2009. The report also reviews some of the activities within the departments aimed at enhancing workplace climate and improving recruitment, retention and promotion of diverse faculty that have been inspired and informed by the CT Project. These activities are funded by a 5 year grant from the National Science Foundation’s ADVANCE Institutional Transformation program, which is designed to create an infrastructure for transforming structures, cultures, and practices in ways that enable and support recruitment, retention and promotion of women faculty in STEM fields. This report represents one step in an overall multistage process. The CT Project will eventually include three additional focal ISU STEM departments, a further synthesis of findings from all departments over a 5-year period, and the development and refinement of assessment tools aimed at identifying and reducing barriers to faculty scholarly success— including issues that hinder the recruitment, retention and promotion of women faculty