The purpose of this research is to explore the motivation of business group firms to adopt pyramidal ownership structures. The traditional approach claims that pyramids are useful in tunneling resources to other affiliates by transferring value to firms with high cash flow rights of controlling shareholders. Using a unique dataset of 7,180 Ecuadorian firms, I analyze the transmission of profits' shocks among group firms to assess the existence and the amount of tunneling. The comprehensive ownership information allows me to identify pyramidal and horizontally owned group firms separately and better understand the nature of their ownership structure. The results provide support for the existence of tunneling in Ecuadorian business groups. About 70% of the profits of the average group firm are transferred to another affiliate, although only half of this money shows up on its books. An alternative explanation for the flow of money among group firms is the existence of internal capital markets to substitute for imperfections in the external market. I test this hypothesis by comparing the impact of cash flow availability in the investment decision of group firms with that of stand-alone firms. Group firms' cash flow to investment sensitivity appears to be only half of the value for comparable standalone firms. Moreover, group liquidity is also a determinant of the average group firm's investment, especially for pyramidal firms. The analysis sheds light on the nature of business groups in Latin America, their ownership patterns, and their resource allocation decisions.

Thesis (M. Sc.)--University of Canterbury, 2007. / Typescript (photocopy). Includes bibliographical references (leaves 74-77). Also available via the World Wide Web.

Thesis (Ph. D.)--University of Chicago, Committee on Neurobiology, August 1999. / Includes bibliographical references. Also available on the Internet.

The prefrontal cortex (PFC) is critically involved in many higher cognitive functions such as goaldirected behaviour, affective behaviour and especially working memory. In vivo extracellular recordings of PFC neural activity during working memory tasks show high variety in observed spiking patterns. These complex dynamics are critically shaped by intrinsic, synaptic and structural parameters of respective prefrontal networks. Moreover, dopamine (DA) is crucial for correct functioning of the PFC during working memory tasks. DA modulates a number of synaptic and intrinsic biophysical properties of single neurons, in particular deep layer pyramidal cells, which represent the major output neurons of the PFC. Despite a high variability of cortical pyramidal cell firing patterns, and somatodendritic morphology, no study has yet systematically examined correlations between intrinsic properties, morphological features and dopaminergic modulation of intrinsic properties. This study investigated properties of deep layer pyramidal cells through whole cell patch clamp in acute brain slices of the adult rat PFC. Cells were characterised physiologically through a variety of stimulation protocols surveying different time scales and wide intensity ranges, while all fast synaptic transmission was blocked. Furthermore the same catalogue of stimuli was recorded whilst applying specific DA receptor agonists to elucidate effects of DA receptor activation on intrinsic properties. All recorded cells were injected with biocytin and dendritic morphology was reconstructed from confocal image stacks of fluorescently labelled neurons. From the resulting data a set of characteristic variables were defined and a combination of principal components analysis and hierarchical cluster analysis was used to identify similarity between recorded cells in different parameter spaces spanned by intrinsic properties, intrinsic properties under dopaminergic modulation and morphology, respectively. The analysis presents evidence for distinct subpopulations within prefrontal deep layer pyramidal cells, as seen by clustering of recorded cells in these high dimensional parameter spaces. These subpopulations also show distinct input-output relationships, bearing implications for computational functions of these subpopulations. Furthermore, this study presents for the first time evidence of subpopulation specific DA effects in deep layer pyramidal cells. The quantitative analysis of somatodendritic morphology confirms physiological subpopulations and identifies characteristic morphological features of deep layer pyramidal cells. Moreover, cluster observed in different parameter spaces overlap, leading to a definition of subpopulations that concurs with previously described prefrontal pyramidal cell types. In conclusion, the results presented provide some deeper insight into fundamental principles of information processing in prefrontal pyramidal cells under the influence of dopamine.

No description available.

The anterior cingulate cortex (ACC) can influence emotional and motivational states in primates by its dense connections with many neocortical and subcortical regions. Pyramidal neurons serve as the basic building blocks of these neocortical circuits, which have been extensively studied in other brain regions, but their morphological and electrophysiological properties in the primate ACC are not well understood. In this study, we used whole-cell patch clamp and high-resolution laser scanning confocal microscopy to reveal the general electrophysiological properties and detailed morphological features of layer 2 and 3 pyramidal neurons in ACC (area 24/32) of the rhesus monkey. Neurons from both layers had similar passive membrane properties and action potential properties. Morphologically, dendrites of layer 3 ACC neurons were more complex than those of layer 2 neurons, by having dendrites with longer total dendritic lengths, more branch points and dendritic segments, spanning larger convex hull volumes. This difference in total dendritic morphology was mainly due to the apical dendrites. In contrast, the basal dendrites displayed mostly similar features between the two groups of neurons. However, while apical dendrites extend to the same layer (layer 1), the basal dendrites of layer 3 extended into deeper layers than layer 2 because of the difference in soma-pia distance. Thus, basal dendrites of the two groups of neurons receive different laminar inputs. Analysis of spines showed that more spines were found in neurons of layer 3 apical dendritic arbors than layer 2 neurons. However, the apical spine densities were similar between neurons in the two layers. Thus, while higher spine number suggests that layer 3 neurons receive more excitatory input than layer 2 neurons, the similar spine density suggests similar spatial and temporal summation of these inputs. The combined effects of increased number of excitatory input and higher dendritic complexity in layer 3 than in layer 2 ACC neurons suggest the additional information received by layer 3 neurons, especially in the apical dendrites, might undergo more complex integration.

Both neuroinflammation, and an increase in microglial cells, have been associated with Autism Spectrum Disorder (ASD) through observation in human subjects as well as in mouse models. A mother having an infection early in pregnancy increases the chances for autism in her child. (Atladottir et al., 2012). This process is known as Maternal Immune Activation (MIA), and the proposed mechanism is that inflammatory signals cross from the mother to child; then in response to increased pro-inflammatory cytokines, microglia within the brain are activated to combat the infection. Microglia are essential to healthy synaptogenesis and neuronal growth, and a change in their signaling early in development has been shown to alter behavior in mouse models that replicate MIA. We use microglial depletion as a therapy to counteract the potentially harmful pro-inflammatory response in the developing mouse brain. Four experimental groups - control, MIA, microglial depleted, and a therapy group (MIA plus microglial depletion)- were run through a comprehensive series of behavioral and electrophysiological assessments. Layer 5 pyramidal cells (L5PNs) were targeted for recording in medial frontal cortex – a mouse cortical area important for cognition and social behavior. L5PNs are a heterogeneous population with cortical and subcortical targeting. Subcortical targeting neurons are thick tufted morphologically, and have an intrinsically bursting spike pattern. Analysis of the intrinsically bursting neurons revealed significant differences between the maternal inflammation and the microglial depletion groups across multiple physiological properties. Therefore, the therapy group had electrophysiological characteristics more consistent with the microglial depleted model than the autism model.

Membre de l'Académie Royale des Sciences, François Pourfour du Petit (1664-1741), ophtalmologue, médecin, chirurgien, botaniste, laisse à la postérité un grand nombre de travaux. Du collège Dormans-Beauvais à l'Académie Royale des sciences, son parcours suit celui de la première révolution biologique amorcée au XVIe siècle. De sa lettre de 1710, on retient la mise en évidence du faisceau pyramidal et de son mémoire de 1727 la requalification du nerf intercostal : de nerf cérébral, il devient nerf spinal. Ses nombreux mémoires sur l'anatomie oculaire, publiés dans l'Histoire et Mémoires de l'Académie Royale des Sciences entre 1727 et 1731 lui donne un rôle de précurseur dans l'histoire de l'ophtalmologie naissante. Mais c'est avant tout une méthode qu'il convient de mettre en avant. Même si le concept de physiologie expérimentale semble appartenir au XIXe siècle, il est le fondement sur lequel s'appuient les investigations anatomiques de François Pourfour Du Petit / Member of the Royal Academy of Sciences of Paris, François Pourfour du Petit (1664-1741), ophthalmologist, doctor, surgeon, botanist, leaves to posterity a large number of works. From Collège Dormans-Beauvais to the Royal Academy of Sciences, his career follows that of the first biological revolution that began in the 16th century. From his letter of 1710, we note the evidence of the pyramidal tract and on his 1727's dissertation, we can retain the requalification of the intercostal nerve : from the cerebral nerve, he becomes a spinal nerve. His numerous dissertations on ocular anatomy, published in the History and Dissertations of the Royal Academy of Sciences between 1727 and 1731, give him a precursory role in the history of nascent ophthalmology. But it is above all a method that should be highlighted. Although the concept of experimental physiology seems to belong to the nineteenth century, it is the foundation on which François Pourfour Du Petit's anatomical investigations are based

The backlight module is usually used to increase visual angle and brightness of liquid crystal display (LCD). Thus, the design and fabrication of optical films, including light guide plate, diffuser film, and brightness enhancement film (BEF), are critical factors to decide the optical efficiency in a backlight module. In order to improve the optical efficiency for power-saved display with competitiveness, this study presents a new fabrication process combining precision machining, lithography, and hot-embossing techniques to form a two-side-patterned optical film. One side of the optical film is micro triangular-pyramidal array (MTPA) and the other is micro spherical lens array(MSLA). First, the Taguchi method is applied to design the optimal microstructure configuration by the assistance of the optical software, FRED. Second, a tungsten (W) steel mold (as the mold to hot emboss MTPA) is manufactured by precision machining including optical projection grinding, lapping, and polishing processes. Meanwhile, a nickel-cobalt (Ni-Co) mold (as the mold to hot emboss MSLA) is fabricated by electroplating process. Then, polydimethylsiloxane (PDMS) is used to replicate the MTPA and MSLA patterns, on W and Ni-Co metal molds, respectively, and the replicated PDMS films are used as the molds to form a two-side-patterned optical film. In addition, the optical property such as luminance is measured by photo research 650 (PR 650) to evidence the optical function of the two-side-patterned optical film. From the experimental results, both brightness and uniformity can be improved by this film;thus, optical efficiency is successfully increased in this study.

Thesis (Ph. D.)--University of Washington, 2000. / Vita. Includes bibliographical references (leaves 104-118).