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A good stereopsis (depth perception) is needed in everyday life, regardless whether a person is a professional driver or chef. Good estimation of distance, and of what is further and what closer, could mean the difference between a crushed and a whole car or between a bloody and a healthy finger. The main theme of this Master thesis is detect and quantify major factors in depth perception. Do the younger estimate the depth better than the older; do they have better depth perception with greater or smaller pupil distance; does depth perception depend on gender; what happens with stereopsis when vision is fogged by +0,5 and +1,0 D? These are the questions dealt with in this Master thesis.
To answer these questions measurements were made on 51 subjects (mean age 45,0 +/- 13,32 years) of whom 25 were women, mean age 45,5 +/-13,55 years (12 with PD<62 mm, mean and 13 with PD>66 mm) and 26 men, mean age 44,4 +/- 13,34 years (13 with PD<62 mm and, 13 with PD >66 mm). Each of these four groups was further divided by age (one in range 20 to 35 years and second in range 50 to 65 years).
The measurements were made with a few assumptions. The first assumption was that stereopsis is in direct correlation with visual acuity, the second assumption was that persons with bigger interpupillar distance have better stereopsis, and the third assumption was that with age the stereopsis ability decreases.
The measurements were done with modified Frisby–Davis test expanded from four geometrical shapes to twenty-five circles. The stereopsis was measured with full refractive correction at 4,5 and 3,0 meters. Later, stereopsis was measured with fogging with +0,5 and +1,0 D at the 4,5 and 3,0 meter distances.
Statistically there is no correlation (or very weak) between stereopsis and the visual acuity for whole group of 51 test persons, but if only young test persons are taken in consideration, the correlation becomes significant, r(20)=0,566, p=0,009 at 4,5 m and r(20)=0,456, p=0,043 at 3,0 m and that matches the assumption. Stereopsis is in no or weak positive correlation with pupil distance r(51)=0,059, p=0,679, which is in total contrast to the assumption. Stereopsis is in positive correlation with age at 4,5 meters measuring distance, r(51)=0,371, p=0,007, which corresponds to assumption. In addition, stereopsis is better in females than in males by 32,5%.
Based on the results it can be concluded that the stereopsis is in negative correlation with age, in positive correlation with visual acuity, females have better stereopsis than males and statistically, the correlation between stereopsis and pupil distance (PD) has not been proved. The most important conclusion is that the decreased visual acuity brings significant fall of stereopsis. A deficit in refraction of -0,50 D decreases stereo acuity by about 90% (nearly 2x) and a deficit of -1,0 D decreases stereo acuity by about 220% (about 3x).
Keywords: Stereopsis, stereo acuity, depth perception, pupil distance (PD), visual acuity (VA).
The present thesis deals with alternative powertrains, focusing on electric vehicles
and hybrid vehicles and which of those alternative powertrains is considered as
sustainable for the future. It explores the question, which alternative powertrain is
worthwhile investing in for German automotive suppliers. The aim is to clarify
which of the two powertrains is already established on the market and what the
future prospects of those powertrains are. The question here is evaluated based on
the analysis of current literature as well as through the use of a SWOT analysis
and the use of the scoring model.
As a result it is clear that there is a need for alternative powertrains and the entire
automotive industry invests a lot in the development and research of alternative
powertrains. According to the German Federal Government, one million electric
vehicles should be on German roads by 2020. With pure electric vehicles, however,
the goal will be difficult to reach. Therefore, there is a lot of vested interest in
the development of hybrid vehicles on the market. It shows that the hybrid vehicle
has considerable advantages over the electric vehicle and the hybrid vehicle is
already seen as a transitional solution for pure electric vehicles. The hybrid vehicle
is also already established in the market and has better chances on the market
in the future. Therefore, it makes sense for German automotive suppliers to invest
in hybrid vehicles and to focus on this market, since there the chances of success
are greater and the future potential of this market is higher.
This paper aims to provide essential information about the formal aspects of the adjustment process companies in Southern Germany utilize to adjust their employees to new surroundings. In particular, it shall be investigated and defined what formal aspects are and when firms apply them. Literature shows that companies do implement language courses, intercultural trainings or provide further information about the host country before a stay abroad. Nevertheless, the phases during and after the assignment are not taken into account with the required importance. Additionally, since national culture can be broken down into different layers, the organizational culture as one layer was analyzed, too.By conducting a quantitative research among companies in Baden-Württemberg, this paper shows the different approaches for dealing with a stay abroad. Scientific literature about the topic of adjustment of globally assigned workers shall help emphasizing the need of a deeper cultural insight. Furthermore, by attempting to explain the organizations’ culture, a better understanding of the chosen training methods shall be created. Definitions in the beginning helped to understand the concept of culture, the notion and the phases of adjustment. Almost all collected data has been accessed either through JSTOR (a digital library founded to help academic libraries or publishers) or similar databases, through the companies’ websites or through the survey results it selves.The results of this research show that the phase before the stay abroad is organized well. Companies offer pre-departure training, but during and after the expatriate time a lack of support is being observed. The firms obviously underestimate the necessary help needed during the assignment and in the return phase, which is why the thesis attempts to fill this gap. Through the organizational culture, described on the companies’ webpages the author was able to draw a conclusion to the applied training methods, which results in a consistent overall picture of the described firms. Companies from the automotive sector had the highest return rate in the survey, which is why particular attention was paid to it.
This paper deals with the question of which factors have to be given for
successful share repurchases that create long-term shareholder value. Center of
the thesis is the agency theory and its influence on share repurchases. Based on
theoretical findings success factors for share repurchases are derived and then
verified by case studies.
The main drivers for a successful share repurchase elaborated by this paper are a
suitable long-term executive compensation, an independent board of directors and
a shareholder structure without a majority shareholder. Additionally the findings
show that tying repurchases to certain share price thresholds improves the quality
of share repurchases.
Aim Patrick J. Caroline and Mark P. Andre first reported about soft lens orthokeratology in 2005. In a number of articles in the past five years, they reported about their research on this topic and their new findings. The aim of this study was to continue the research of Patrick J. Caroline and Mark P. Andre and to collect more information about the outcome of the technique. Methods Ten subjects with low myopia from -0.25 D to -1.25 D and a refractive astigmatism from plano to -0.75 D were fitted with a -10.00 D CIBA VISION AIR OPTIX® NIGHT&DAY® silicone hydrogel contact lens and were told to wear the lenses over night and everted. Corneal topography and refraction measurements were taken after one night, one week and one month of contact lens wear. Results Eight out of ten subjects finished the study, six female and two male. The mean age of the subjects was 23.9 years. With the eight subjects who finished the study, the mean change in subjective refraction was about +1.00 D in the sphere and +0.22 D in the cylinder, with maximum changes of +1.75 D sphere and +0.75 D cylinder. The mean apical power change, measured with the topographer, was 1.11 D. Changes in K - readings ranged from slight corneal steepening in both of the meridians to 0.23 mm of corneal flattening in the horizontal meridian and 0.27 mm of corneal flattening in the vertical meridian. Corneal eccentricity decreased about 0.65 on average. The main complaints and problems were the high minus power and the decentration of the contact lens and the occurrence of ghosting at night. Conclusion The results of this study show that everted wear of a high minus silicone hydrogel contact lens can lead to orthokeratology - such as changes in corneal topography and subjective refraction. These changes range from plano to +1.75 D sphere and +0.25 D to +0.75 D cylinder but are unpredictable and vary from subject to subject. Additional studies regarding the contact lens decentration and the unpredictability of the outcome need to be done to optimize the process.