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Christina Colby
....Department of Psychology
....Mentor: Prof. Elizabeth Lorch
The Development of Story Recall and
Attention in Children with Attention
-Deficit Hyperactivity Disorder (ADHD)
and Comparison Children

The current study investigated how salient distracters, such as toys, affect attention to televised stories. Furthermore, this study examined how differences in attention related to story comprehension in younger and older children with ADHD as compared to nonreferred children. Each child watched two "RUGRATS" episodes with two viewing conditions, toys and no toys. After each episode an experimenter asked the child to answer 35-38 questions about the show. Children with ADHD showed a significantly greater decrease in visual attention in the toys condition compared to the nonreferred children. Children with ADHD comprehended discrete factual events as well as comparison children in the absence of toys. However, in the presence of toys, older but not younger children with ADHD decreased performance on factual questions. Although both older groups answered more causal questions than younger children, older comparison children did better at understanding causal relations than older children with ADHD. By knowing more about how the attention of children with ADHD affects their ability to encode cohesive stories, the more we will understand about the development of difficulties faced by these children. With such knowledge, programs can be implemented to help alleviate the social and academic problems that affect children with ADHD.

Bruno deHarak
....Department of Physics
....Mentor: Prof. Dan Dale
Optical Properties of Lead Tungstate
Crystals

The PrimEx collaboration has the goal of performing a high precision measurement of the lifetime of the neutral pion (p0). The hybrid calorimeter (HYCAL) will perform the essential function for this experiment of detecting the two photons emitted when the pion decays. The HYCAL, will utilize lead tungstate scintillating crystals (manufactured by the Shanghai Institute of Ceramics) and lead glass Cherenkov shower counters. A study of the optical properties of each of the individual lead tungstate crystals to be used in the HYCAL has been performed. The results of this study as well as the details of the techniques used will be presented in this paper.

 

In order to perform an analysis of the optical properties (primarily transmittance and reflectance for wavelengths of approximately 300 to 800 nm) of all of the lead tungstate crystals for use in the HYCAL, a single crystal was first studied. This was done to develop and proof the equipment and techniques being used. This initial analysis has been performed and some of the specific results are as follows:

  • The index of refraction for the crystal was mea- sured using two techniques, the first by using a laser to directly measure the angles of incidence, reflection, and refraction; the second by polariz- ing a laser and determining Brewster's angle. The index of refraction differs somewhat from those values published in various journal articles. The index of refraction is needed to determine the re- flectance and transmittance of the crystal.
  • The CCD detector being used provides a linear response, which is necessary to perform the planned transmittance measurement.
  • Filtering of the light source is necessary to elimi- nate contamination by higher as well as lower order wavelengths while measuring the flux of a particular wavelength.

The initial study of a single crystal has been completed and the project is now in the design phase. Equipment and software is being designed to automate the measurement of all the lead tungstate crystals for the HYCAL. The equipment will consist of a translation platform with a small elevator and associated circuitry, a light source with collimator, a spectrophotometer with a CCD detector, and a computer acting as a control station for the spectrophotometer and CCD. Once a set (approximately 20) of crystals has been installed on the platform, no further manual intervention will be required.

Once the design is complete it is expected that construction and troubleshooting will take an additional 1 to 2 weeks. Data acquisition and analysis will follow immediately. The timeframe for this final phase of the project is largely dependent on the variations found in the crystals as they are studied.

Ryan Gabbard
....Department of Computer Science
.... Mentor: Prof. Jerzy Jaromczyk
Multiple Views of XML Documents

Extensible Markup Language (XML) is the standard format for the interchange of structured data by computers. This project explores data structures and

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