The purpose of this study was to determine the effects of auditory background interference on test performance on a group of schizophrenics as well as with a normal group and to ascertain if subgroups of each type could be differentiated on neuopsychological measures from the WMS-R particularly sensitive to left-hemispheric functions.There were 60 subjects, 30 normals and 30 schizophrenics, who volunteered to participate in the study. The schizophrenics, all hospitalized at Logansport State Hospital, had a diagnosis of chronic undifferentiated schizophrenia. The normals were students at Logansport High School enrolled in a senior psychology class. The research utilized a counterbalanced design in which subjects were administered items from the Wechsler Memory Scale-Revised in both a normal administration condition and in the presence of auditory background information provided by a prerecorded tape.The relationship between auditory background interference and diagnosis was examined using an analysis of variance (MANOVA) of the difference between means. The overall mean for groups did not differ significantly, F (1,58) = .087. No test was identified as being able to differentiate left-hemispheric functions for either group in either testing condition, F (4, 55) = 1.09, p .37. There also was no statistically significant difference between the test performance of males and females in the presence of auditory background interference.The results indicate that neither group evidenced much change in perfromance in the presence of auditory background information. This would suggest that the testing conditionn had little influence on test results. It also suggests that internal differences, as opposed to the external environment, contributed much more to the differences in test performance. The lack of significant differences on the subtests that are considered measures of left-hemispheric functioning may have been due to the significant cognitive impairments of the schizophrenics. The normals may have been more able to increase their attentional and concentration skills in the presence of auditory background interference so that no decreases in performance resulted. / School of Physical Education

The aim of this study was to determine in an empirical manner whether the phenomenon of hearing loss due to the exposure to volatile organic solvents was present in the gasification plants of a petrochemical factory. The experimental groups included unexposed (N=20) workers, workers (N=20) exposed to noise and workers (N=19) exposed to noise and volatile organic solvents. The following assessments were made: diagnostic audiometry for the assessment of hearing thresholds; biological monitoring of ortho-cresol and hippuric acid for the biological markers of toluene; passive air sampling and noise measurements. Questionnaires were completed by the three groups to collect information about age, ethnicity, smoking habits, alcohol consumption and work history regarding the exposure to ototoxic substances as well as the period of employment. There were no statistically significant differences between the average ages of the three groups, but more of the workers in the noise group were from a higher age group. This age composition and the work history of the noise group were considered as possible influences on the results of this hearing study. The results of the passive air sampling show that the levels of volatile organic solvents were lower than the occupational exposure limits on the day of sampling. The biological monitoring shows that the markers, namely hippuric acid and o-cresol, were lower than the biological exposure indices. The noise group was exposed to sound pressure levels of 79-90 dB(A) and the noise + hydrocarbon group to levels of 85-88 dB(A). The average hearing thresholds of the noise group were at most of the frequencies (0.5-8 kHz) significantly higher (p≤0,05) than that of the noise + hydrocarbon group. The average hearing thresholds of the control group were overall lower than the noise group's hearing thresholds, but on average a little higher than the noise + hydrocarbon group's hearing thresholds. No relationship was found in this study between the exposure to volatile organic solvents (for example toluene that was used as marker in this study) and the elevation of hearing thresholds of workers at the gasification plants of the petrochemical factory. / Thesis (M.Sc.)--North-West University, Potchefstroom Campus, 2004.

Psychologists have found that noise reduces human efficiency. This effect may be considerable even for the most phlegmatic individuals. Moreover, almost everyone objects to unnecessary noises. In recent years there has arisen a very insistent demand for quieter electrical apparatus. This applies particularly to household apparatus such as refrigerator motors, vacuum sweepers and the like. Practically noiseless motors are also required for various drives ( refrigerating plants, circulation pumps of hot water systems, big ventilating systems for rooms, organ bellows etc. ) in non industrial plants such as storerooms, business houses, hotels, hospitals, churches, theatres etc> where all noise should be suppressed. It must also be noted that the stage has been reached where it is taken for granted that the products of the better known manufacturers will give entirely satisfactory performance, and often, the deciding factor between various makes is only the quietness with which the equipment operates. However,noise and vibration are not merely annoyances which may affect the sale of a product or lower the efficiency of a worker. They are often evidences of defects in design and manufacture which seriously affect the life of the equipment and, in many cases, the safety of the user.[...]

This thesis considers the nature of information management on the World Wide Web. The web has evolved into a global information system that is completely unregulated, permitting anyone to publish whatever information they wish. However, this information is almost entirely unmanaged, which, together with the enormous number of users who access it, places enormous strain on the web's architecture. This has led to the exposure of inherent flaws, which reduce its effectiveness as an information system. The thesis presents a thorough analysis of the state of this architecture, and identifies three flaws that could render the web unusable: link rot; a shrinking namespace; and the inevitable increase of noise in the system. A critical examination of existing solutions to these flaws is provided, together with a discussion on why the solutions have not been deployed or adopted. The thesis determines that they have failed to take into account the nature of the information flow between information provider and consumer, or the open philosophy of the web. The overall aim of the research has therefore been to design a new solution to these flaws in the web, based on a greater understanding of the nature of the information that flows upon it. The realization of this objective has included the development of a new model for managing information flow on the web, which is used to develop a solution to the flaws. The solution comprises three new additions to the web's architecture: a temporal referencing scheme; an Oracle Server Network for more effective web browsing; and a Resource Locator Service, which provides automatic transparent resource migration. The thesis describes their design and operation, and presents the concept of the Request Router, which provides a new way of integrating such distributed systems into the web's existing architecture without breaking it. The design of the Resource Locator Service, including the development of new protocols for resource migration, is covered in great detail, and a prototype system that has been developed to prove the effectiveness of the design is presented. The design is further validated by comprehensive performance measurements of the prototype, which show that it will scale to manage a web whose size is orders of magnitude greater than it is today.

Syntactic foams-composite materials consisting of hollow particles embedded in a host matrix-have many applications for manufactured products, including weight reduction, thermal insulation, and noise reduction. In this thesis, a certain variety of syntactic foam is investigated with regards to reducing fluid borne noise in hydraulic systems. Such a foam maintains stiffness at low hydrostatic pressures and becomes compressible as pressure increases. With this compressibility, the foam is potentially useful as a liner for a reactive noise control device, much like compressed gas style devices currently in use; but the syntactic foam additionally adds significant damping to the system. In order to predict device performance, a linear multimodal model is developed of a hydraulic suppressor, constructed as an expansion chamber lined with a syntactic foam insert. Material models are developed for various compositions of the foam liners, based on an inverse analysis matching the model to experimental results. Two model simplifications are considered, and it is found that a simplified bulk modulus model gives sufficiently accurate results to make approximate predictions of suppressor performance. Several optimizations are performed to predict the optimal material composition for hydraulic excavator work cycles. To help compare the prototype suppressor against commercially available bladder style suppressors, a model is developed for the bladder style silencer and is validated experimentally. Overall, this work both demonstrates the current and potential utility of syntactic foam as a device lining material, and contributes new models to the hydraulics noise control community.

We consider observations of a random field (or a random process), which is modeled by a nonlinear regression with a parametrized mean (or trend) and a parametrized covariance function. In the first part we show that under the assumption that the errors are normal with small variances, even when the number of observations is small, the ML estimators of both parameters are approximately unbiased, uncorrelated, with variances given by the inverse of the Fisher information matrix. In the second part we are extending the result of Pazman & Müller (2001) to the case of parametrized covariance function, namely we prove that the optimum designs with and without the presence of the virtual noise are identical. This in principle justify the use the method of virtual noise as a computational device also in this case. (authors' abstract) / Series: Research Report Series / Department of Statistics and Mathematics

A system for exciting Rubidium atoms to Rydberg states has been constructed to study the interactions between them and metal surfaces. This thesis describes a method to reach the f Rydberg series using diode lasers. Since the diode lasers need to be frequency stabilized for this excitation, a transfer cavity stabilization method was implemented using the Pound-Drever-Hall technique. To obtain the necessary frequency modulation the diode laser was current modulated at ∼ 6 MHz. A noise cancellation circuit was used to suppress detection of the accompanying residual intensity modulation.

In practice, quantum systems are not completely isolated from their environment and the resulting system-environment interaction can lead to information leakage from the system. As a result, if a quantum system is to be used for storing or manipulating information, one would like to characterize these environmental noise effects. Such a characterization affords one the ability to design robust methods for preserving the information contained in the system. Unfortunately, completely characterizing the noise in a realistic amount of time is impossible for even moderately large systems. In this thesis we discuss methods and diagnostics for partially characterizing quantum noise processes that are especially useful in quantum information and computation. We present a randomized benchmarking protocol that provides a scalable method for determining important properties of the noise affecting the set of gates used on a quantum information processor. We also prove various properties of the quantum gate fidelity, which is a useful state-dependent measure of the distance between two quantum operations, and an important diagnostic of the noise affecting a quantum process. Some non-intuitive generic features of quantum operations acting on large-dimensional quantum systems are also presented.

Thesis (Ph.D.)--University of Hawaii at Manoa, 1994. / Includes bibliographical references (leaves 212-216). / Microfiche. / xiii, 216 leaves, bound ill. 29 cm

This thesis reports on a design and modeling of a micro-machined gyroscope. The proposed sensor is a dual mass type, electro-statically driven to primary mode oscillation and senses, capacitively, the output signal. Full decoupling between drive and sense modes minimizes the mechanical crosstalk and based on this a novel gyroscope is designed and modeled which has separate sensing and driving masses. The dual mass gyroscope is designed such that driving and sensing resonant frequency is 23101 Hz with 0% mismatch (in simulation)with quality factor of 31.6227 and bandwidth of 730.51Hz. The gyroscope when actuated in simulation with 25V ac and 10V dc showed sensing capacitance variation of 126aF for 1 rad/s with base capacitance of 244.16fF. To the design of the gyroscope a new semi automatic tool was formulated for the noise analysis and noise based optimization of the resonant MEMS structures. Design of a sensitive gyroscope needs to take into account the noise shaping induced by damping phenomena at micro scale and is critical for optimization. The analysis was further extended to the design of the gyroscope and estimation shows that there is a trade of between the S/N ratio and the sensitivity and the design could be made much better in-terms of S/N by tuning its resonant frequency to 10⁶Hz.