Approach and avoidance responses to a Tat dimension as related to reaction time and galvanic skin response on a word association test

Thesis (M.S.

Rapid adaptive evolution of colour vision in the threespine stickleback radiation.

Vision is a sensory modality of fundamental importance for many animals, aiding in foraging, detection of predators and mate choice. Adaptation to local ambient light conditions is thought to be commonplace, and a match between spectral sensitivity and light spectrum is predicted. We use opsin gene expression to test for local adaptation and matching of spectral sensitivity in multiple independent lake populations of threespine stickleback populations derived since the last ice age from an ancestral marine form. We show that sensitivity across the visual spectrum is shifted repeatedly towards longer wavelengths in freshwater compared with the ancestral marine form. Laboratory rearing suggests that this shift is largely genetically based. Using a new metric, we found that the magnitude of shift in spectral sensitivity in each population corresponds strongly to the transition in the availability of different wavelengths of light between the marine and lake environments. We also found evidence of local adaptation by sympatric benthic and limnetic ecotypes to different light environments within lakes. Our findings indicate rapid parallel evolution of the visual system to altered light conditions. The changes have not, however, yielded a close matching of spectrum-wide sensitivity to wavelength availability, for reasons we discuss

Noise Control Concept Verification for a Ducted Fan System

The noise level of consumer products is a growing concern for manufacturers since customers’ product sound quality expectations are increasing. The product that motivated the present work was a “bladeless” fan in which the rotor and stator module were located in the base of the unit. Direct intensity measurements were used to characterize the fan’s acoustical output, which was found to radiate primarily from the air inlet beneath the rotor in the base unit. The noise control design concept explored here is based on the dipole characteristic of axial fans. It has been shown previously that when only one side of the fan is connected to the exterior sound field, the radiation is monopole-like. But, by exposing both sides of the dipole to the exterior field, the radiation efficiency of the source is reduced, and hence the sound power is reduced compared to a situation in which only one side of the fan connects with the exterior field. That concept is applicable not just to the bladeless fan investigated in this work, but could also find application in other ducted fan systems. The monopole-to-dipole source conversion approach is demonstrated here both numerically and experimentally based on a simplified model of the fan base unit

A Desktop Procedure for Measuring the Transmission Loss of Automotive Door Seals

Due to the increasing concern with the acoustic environment within automotive vehicles, there is an interest in measuring the acoustical properties of automotive door seals. These systems play an important role in blocking external noise sources, such as aerodynamic noise and tire noise, from entering the passenger compartment. Thus, it is important to be able to conveniently measure their acoustic performance. Previous methods of measuring the ability of seals to block sound required the use of either a reverberation chamber, or a wind tunnel with a special purpose chamber attached to it. That is, these methods required the use of large and expensive facilities. A simpler and more economical desktop procedure is thus needed to allow easy and fast acoustic measurement of automotive door seals. In the present work, a desktop, four-microphone, square cross-section standing wave tube was modified by the addition of a new sample holder to make it possible to measure the transmission loss of door seals under various states of compression. In this new procedure, the sample is clamped between a sliding piston and one wall of the standing wave tube. Since the clamp partially blocks the channel, thus impacting the measured transmission loss, a correction is necessary to determine the transmission loss of the seal by itself. Therefore, an initial set of measurements was performed to identify the correction factor required to adjust the measured transmission loss of the clamp plus seal to eliminate the contribution of the clamp itself. Once the accuracy of the correction procedure was verified, a number of typical door seals were tested at various degrees of compression. The transmission losses of the seals were generally in excess of 30 dB, and the transmission loss was found to increase significantly as the seals were compressed. The latter point, in particular, indicates that careful design of the seal mounting arrangements in the vehicle is crucial to ensuring their optimal performance

The Early Retirement Burden: Assessing the Costs of the Continued Prevalence of Early Retirement in OECD Countries

Despite substantial increases in longevity, the age of retirement in the industrialized countries has steadily fallen throughout most of the 20th century. In France, for instance, the employment-population ratio of 55-64 year-old males fell from 74% in 1970 to 38.5% in 2000. In most other OECD countries, labor force participation rates for those 65 and above have fallen significantly. The economic cost of low labor market participation, in terms of lost output, benefit payments, and lower tax base is substantial. However, part of the cost of low labor market participation is cyclical or structural and hence separate from the costs of early retirement. This paper develops a simple framework to assess the specific costs of early retirement and applies it using data from the OECD countries. More significantly, we find that the costs associated with early retirement are projected to rise considerably in the next ten years from 7.6% of output in 2003 to 9.1% of output in 2010. This projected rise in the costs of early retirement over the course of the rest of the decade is slightly larger than the percentage point rise in the costs of early retirement over the twenty year period from 1982 to 2003. The projected rise in costs over the course of the next decade is largely due to population ageing, whereas the rise in costs over the past twenty years was primarily due to lower labor force participation of older workers

Bisecting binomial coefficients

In this paper, we deal with the problem of bisecting binomial coefficients. We find many (previously unknown) infinite classes of integers which admit nontrivial bisections, and a class with only trivial bisections. As a byproduct of this last construction, we show conjectures Q2 and Q4 of Cusick and Li [7]. We next find several bounds for the number of nontrivial bisections and further compute (using a supercomputer) the exact number of such bisections for n ≤ 51

Near-Field Acoustical Holography Incorporating Compressive Sensing

To identify sound source locations by using Near-field Acoustical Holography (NAH), a large number of microphone measurements is generally required in order to cover the source region and to ensure a sufficiently high spatial sampling rate. It may be the case that hundreds of microphones are required, so such measurements are economically expensive, which has limited the industrial application of NAH to the identification of sound source locations. Recently, however, it has been shown possible to identify concentrated sound sources with a limited number of microphone measurements based on Compressive Sampling theory. In the present work, a loudspeaker was used as a sound source and a near-field intensity scan was conducted to measure the true sound field and sound power generated by the loudspeaker. Then by using exactly the same measured data, four NAH methods were used to reconstruct the sound field: i.e., Statistically Optimized Near-Field Acoustical Holography (SONAH), Wideband Holography (WBH), l1-norm minimization and a hybrid compressive sampling method. The number of microphone measurements used to reconstruct the sound field was decreased systematically by increasing the spacing between microphones. Then the reconstruction results were compared with the measured intensity results, and the benefits of the compressive sensing are illustrated