dissertation com do not use dez 2000 (4 résultats)

Taschenbuch. Etat : Neu. Neuware - This thesis is divided into 4 chapters summarizing this contribution on selected topics related to chlorophyll biosynthesis and biogenesis of the photosynthetic apparatus. The first chapter deals with the state of Pchlide in nonilluminated leaves. The comparison of the photoactive Pchlide absorbance spectra throughout the development in the dark, reveals that the proportion of P638-645 and P650-657 is not much modified during this period. The Gaussian deconvolutions of 77 K fluorescence spectra of nonphotoactive and photoactive Pchlide indicated the presence of three and 5 spectral forms, respectively. None of the nonphotoactive Pchlide forms is accumulated during the dark-growth. In constrast, photoactive Pchlide P650-657 is particularly accumulated. In the second chapter, we describe the photoreduction of Pchlide to Chlide. We conclude that the mechanism of photoreduction is independent on the leaf developmental stage. Using 77 K fluorescence spectroscopy, the Chlide spectral forms corresponding to the three photoactive Pchlides were identified. In leaves with proplastids, C670-675 is mainly formed whereas in leaves with etioplasts C684-696 is produced. During the 1st hour of greening, the newly formed Chlide molecules are not protected by carotenoids. The evidence for the involvement of a photocycle involving two spectral forms of Chlide in protection of newly formed Chlide is presented. In the third chapter, a method for the isolation of photoactive Pchlide yielding complexes characterized by spectral properties similar to those found in intact leaves is described. In the fourth chapter, it is explained that the different fates of the first products of the photoreduction, described in the 2nd chapter, influence the greening process. In fact, C684-696 is only produced in small amounts in plants with proplastids. Therefore the increase of the photosynthetic activity of these leaves is delayed. Nevertheless, during the first 8 h of greening, a weak photosynthetic activity is detected in these leaves. Fluorescence measurements reveal that a large part of the Chl remains nonintegrated to the photosystems. In young leaves, rapid Chl integration into the photosynthetic units occurs when both carotenoids and Chl are massively synthesized.

Taschenbuch. Etat : Neu. Neuware.

Taschenbuch. Etat : Neu. Neuware - The purpose of this study was to examine the effect of clarifying students' misperceptions regarding their peers' consumption of alcohol and feelings of comfort in drinking situations. Quantitative and qualitative approaches were used to determine if providing students with information would impact on their perceptions. A posttest-only control-group experimental design was employed to investigate the efficacy of clarifying students' misperceptions. The experimental group was provided with information gleaned from the literature regarding students' misperceptions. Participants were administered a questionnaire developed for this study to determine: (a) their drinking habits (i. e., frequency and quantity), (b) how comfortable they feel in drinking situations, (c) their perceptions regarding their peers' drinking habits, and (d) their perceptions regarding how comfortable their peers feel in drinking situations.The findings included: (a) students overestimated the alcohol consumed by their peers; (b) students inaccurately believed that their peers are more comfortable in drinking situations than they are themselves; and (c) information appears to have clarified female students' misperceptions associated with feelings of comfort in drinking situations. A theory grounded in reality (Corbin.

Taschenbuch. Etat : Neu. Neuware - (Complete work in Spanish) The doctoral thesis contributes to some related Management Control areas such us Mergers and Acquisitions (M&A) and the informal components of Control Systems. The objective of the research was to analyse how this process of business concentration may impact on the Management Control System of the acquired firm. For this purpose an alternative theoretical model have been developed from the review of Management Control literature and M&A in Management Accounting. This model builds on contingency theoretical insights and extends it with elements of informal control.To test the prepositions a single ethnographic in-depth case study was carried out. It was conducted in a Spanish subsidiary of an English chemical group during 31 months. The main findings of this research are related to the role of (1) both non-formal and formal mechanisms and, specially, (2) top management within this process of organizational change. Besides, it should be highlighted that one of the more interesting studied issues in our case was the analysis of the Spanish versus Anglo-Saxon Management styles.