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"Creath, Katherine"
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Effects of musical sound on the germination of seeds
A series of five experiments were performed to determine if musical sound had a different effect than non-musical sound on the germination of zucchini and okra seeds when compared to a control. Musical sound for this study was a collection of improvised works performed by R. Carlos Nakai and Paul Horn. Predominant instrumentation was different types of flute with some selections for soprano saxophone or bass voice. Non-musical sound was “pink” noise used to test loudspeakers. The first three experiments compared musical sound to a control. The last two experiments compared musical sound to non-musical sound to a control. The number of seeds that had sprouted was counted every 12 hours over a 72-hour time span. Data from the germination of 3,600 seeds over a total of 14 runs for the five experiments were examined using five-way analyses of variance of mixed design. The main effect for musical sound versus control over all five experiments was highly significant (p < 0.002). Positional location, temperature and seed type were shown not to be factors. Over the eight runs of the last two experiments (2,400 seeds) there were no significant interactions between non-musical sound and control. The two-way interaction between condition and time for the three conditions of musical sound, non-musical sound and control was statistically significant (p < 0.03) indicating that the musical sound used for this study had a greater effect than the non-musical sound. These results imply that effects of musical sound extend beyond the psychological and suggest the possibility that musical sound can have physiological effects on biological systems.
Dissertation
DIGITAL SPECKLE-PATTERN INTERFEROMETRY (OPTICAL TESTING)
A digital speckle-pattern interferometer was built utilizing a 100 x 100 element Reticon diode array interfaced to an HP-9836C desk-top computer. A single-mode optical fiber mounted in the center of the system's aperture stop creates a spherical-wave reference beam. Secondary interference fringes are calculated inside the computer by subtracting speckle patterns before and after a deformation, and squaring this difference. This technique has been shown superior to that of taking the absolute value of the difference. The traditional vibrational observation technique of low-pass filtering a single speckle pattern and squaring the result is emulated in software. It is compared to four other vibration observation techniques. A new technique records the self-interference terms in a reference frame, and subtracts these from the time-averaged vibration data. It provides very good fringe contrast for moderately unstable objects, as well as interferometers which have not been optimized to minimize self-interference terms. The best vibration fringe contrast is obtained by subtracting two time-averaged speckle patterns of a single object resonance. One exposure has a relative (pi) phase-shift between object and reference beams to cancel self-interference terms. This last technique is not real-time; whereas, the new technique is. Double-exposure speckle interferograms are averaged using a technique which utilizes a stepping motor to change the object illumination angle. Results of averaging deformation measurements and double-exposure vibration techniques show a large increase in fringe contrast with an accompanying reduction in speckle noise. Quantitative measurements of object deformations is demonstrated by applying phase-shifting interferometry techniques. A deformation's phase is found by subtracting modulo 2(pi) phases measured for each object state. Phase discontinuities are removed with the aid of noise reduction algorithms. Limitations are low intensity modulation as the phase is shifted, and speckle decorrelation during object deformation. It is shown that 10 waves of object deformation are measurable to (lamda)/10 across the detector array. The double-exposure phase-measurement technique works well and is applicable to many different metrological measurements. To show the versatility of this technique, an optically smooth surface is contoured using two illumination wavelengths.
Dissertation
Self-triggered assistive stimulus training improves step initiation in persons with Parkinson’s disease
Background
Prior studies demonstrated that hesitation-prone persons with Parkinson’s disease (PDs) acutely improve step initiation using a novel self-triggered stimulus that enhances lateral weight shift prior to step onset. PDs showed reduced anticipatory postural adjustment (APA) durations, earlier step onsets, and faster 1
st
step speed immediately following stimulus exposure.
Objective
This study investigated the effects of long-term stimulus exposure.
Methods
Two groups of hesitation-prone subjects with Parkinson’s disease (PD) participated in a 6-week step-initiation training program involving one of two stimulus conditions: 1) Drop. The stance-side support surface was lowered quickly (1.5 cm); 2) Vibration. A short vibration (100 ms) was applied beneath the stance-side support surface. Stimuli were self-triggered by a 5% reduction in vertical force under the stance foot during the APA. Testing was at baseline, immediately post-training, and 6 weeks post-training. Measurements included timing and magnitude of ground reaction forces, and step speed and length.
Results
Both groups improved their APA force modulation after training. Contrary to previous results, neither group showed reduced APA durations or earlier step onset times. The vibration group showed 55% increase in step speed and a 39% increase in step length which were retained 6 weeks post-training. The drop group showed no stepping-performance improvements.
Conclusions
The acute sensitivity to the quickness-enhancing effects of stimulus exposure demonstrated in previous studies was supplanted by improved force modulation following prolonged stimulus exposure. The results suggest a potential approach to reduce the severity of start hesitation in PDs, but further study is needed to understand the relationship between short- and long-term effects of stimulus exposure.
Journal Article