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Abstract In this paper, the optical properties of magnetic fluid thin films are studied. We present the experimental observation of optical linear birefringence and dichroism in magnetic fluid thin film induced by crossed magnetic field perpendicular to the direction of light propagation. According to our results, we ascertain that both the magnetic birefringence and dichroism are existed. Besides, we also find that the relations between magnetic field and magneto-optical effects changed with the applied magnetic field intensity.

In this thesis, the study of optical properties of magnetic fluid thin films is the main purpose. We measured the intensity of linear polarized laser beam, which passed through our sample, magnetic fluid thin film with external magnetism, to analyze the relationships between magnetic field intensity and magneto-birefringence and magneto-dichroism. According to our experimental results, we ascertain that both the magneto-birefringence and magneto-dichroism are existed. Besides, we found that the difference of index at magnetic fluid thin film changed with magnetic field intensity also. The phenomenon let us believe that magnetic fluid thin film is anisotropy. Moreover, we also applied the statement, which agreed by most physicists to explain what we found from our real measurements.

The coloration of plumage and ornaments in the groups Numididae, Odonthophoridae and Phasianidae (within the order Galliformes) was detailled described and analyzed. The ecological factors affecting the evolution of dichromatism and conspicuousness were tested.

This study is the first to quantify pelage sexual dichromatism (PelSD) across the order Primates. The hypothesis that PelSD evolves as a consequence of sexual selection on the pelage color of male primates is considered. Color-corrected high-resolution photographs were taken of primate pelts taken from museum collections, representing primate 83 species. Two measures of color, luminance and hue, were taken for the dorsal and ventral aspects of the trunk of each specimen. These measurements are proxies for the absolute and relative concentrations of melanin(s) in primate pelage. Highly-dichromatic species were identified and the evolution of luminance and hue in males and females of those species was analyzed. Species where male luminance or hue was under selection without concomitant selection on females were considered to be under sexual selection. There was little clear evidence of sexual selection on male luminance in highly-dichromatic species. However, there was substantial evidence of sexual selection on male hue. To determine if male pelage color is an ornament that signals quality and is used by females in choosing mates, fluctuating asymmetry (FA), a proxy for mate choice, was regressed against PelSD. Evidence of trunk pelage as ornamentation (i.e., significant correlation between FA and PelSD) was only observed among platyrrhines. Sexual selection on male hue and a trend toward yellower pelage in males of highly-dichromatic species suggests a shift to phaeomelanin production in those males. Explanations for the observed shift to yellow pelage/phaeomelanin production are explored. / Anthropology