The discovery of stem and progenitor cells capable of ongoing neurogenesis in the adult mammalian brain has raised hope that we will one day be able to harness their intrinsic regenerative capacity following injury. Development of such therapeutic strategies relies on a comprehensive understanding of the underlying regulation of the neurogenic process. To this end, I show, in this thesis, that cultured post-natal hippocampal neural progenitor cells (NPCs) express a specific repertoire of connexins (Cx), a family of channel forming proteins critical for communication prior to the development of functional chemical synapses. I show that this pattern of Cx expression, specifically Cx43 and Cx45, is modulated by interaction with the extracellular matrix component laminin providing evidence of extracellular matrix-cell interaction in the regulation of intrinsic Cx expression and function in postnatal NPCs. In adult brain, I show, for the first time, that Cx45 localizes to all cell types of the neuronal lineage with the exception of the type 3 doublecortin (DCX)-positive NPCs. Using a loss of function approach, I show that this expression is required for the normal proliferation of type 1 nestin and glial fibrillary acidic protein-positive stem like NPCs but not for the differentiation or survival of their progeny in the adult hippocampus. With respect to exogenous pharmacological cues that influence hippocampal neurogenesis, this thesis also demonstrates that chronic treatment with a sub-set of selective serotonin reuptake inhibitor antidepressants, fluoxetine and escitalopram, increases the proliferation but not the survival of adult NPCs in healthy, non-depressed mice. Further, standard post-operative analgesia with the opiate buprenorphine inhibits the proliferation of DCX-positive adult NPCs and increases the survival of their progeny. Finally, over the course of the research for this thesis, it became clear that exposing research animals to even very subtle environmental changes can influence the basal neurogenic process. Ultimately this work further highlights the exquisite sensitivity of the regulation of what is already recognized to be a highly dynamic process and provides important insight into the neurogenic process that can be used to inform future therapeutic development and application.

At the author’s request, the abstract has been removed due to the confidential nature of the thesis. It will be added once the embargo period has passed.

La nano-structuration de matériaux semiconducteurs à grand gap à base de GaN fait l'objet d'un très grand intérêt de par son potentiel pour l'élaboration de composants optoélectroniques innovants émettant dans la gamme spectrale de l’ultraviolet. Le contrôle de la croissance à l'échelle nanométrique doit être ainsi démontré. L'épitaxie sélective ou SAG (Selective Area Growth) étendue au domaine nanométrique (NSAG pour NanoSAG) est un excellent choix pour l'élaboration de nanostructures de semiconducteur. Cette technique consiste en la croissance localisée du matériau sur un substrat partiellement recouvert d'un masque en diélectrique. La NSAG permet l'élaboration d'hétéro-structures en fort désaccord de maille grâce aux mécanismes singuliers de relaxation des contraintes à l'intérieur des nanostructures qui réduisent considérablement la densité de dislocations créées. La première partie de la thèse porte sur la mise en œuvre de l'épitaxie sélective du GaN sur pseudo-substrat de GaN à l'échelle micrométrique puis nanométrique par la technique d'épitaxie en phase vapeur aux organométalliques. Dans un deuxième temps, la NSAG est utilisée pour l'épitaxie de nanostructures de GaN sur substrats de SiC-6H et pseudo-substrat d'AlN. L'influence des conditions de croissance et des motifs définis dans le masque sur la forme des nanostructures est étudiée par la microscopie électronique à balayage et la microscopie à force atomique. Finallement la microscopie électronique en transmission et la nano-diffraction des rayons X par rayonnement synchrotron sont utilisées pour l'analyse structurale approfondie des nanostructures / GaN based wide bandgap semiconductor materials nanostructures have a tremendous potential of applications for innovative optoelectronic devices emitting in the UV region (190-340nm). Thus, the feasibility of the nanoscale growth must be demonstrated. Selective Area Growth (SAG) extended to the nanoscale (NSAG for NanoSAG) is an excellent approach for growing semiconductor nanostructures. This technique is based on localized growth of the material on substrates partially covered by dielectric masks. NSAG technique allows the growth of highly mismatched materials because the density of dislocation is reduced thanks to singular stress relief mechanisms that occur at nanoscale. The first part of the work consists in the implementation of the GaN selective epitaxy on GaN template substrate at the micrometer and nanometer scales by Metal Organic Vapor Phase Epitaxy. In a second time, the NSAG technique is used for the growth of GaN nanostructures on SiC-6H substrate and AlN template substrate. The influence of the growth conditions and the mask pattern on the nanostructures shape is demonstrated using Scattering Electronic Microscopy and Atomic Force Microscopy. Fine structural analysis of the nanostructures is finally investigated using advanced characterization tools such as Transmission Electron Microscopy and X-rays nano-diffraction by synchrotron radiation

The work analyzes the development and salary differentiation in the Czech Republic and focuses on the wage differentials between men and women. It evaluates the impact of factors, which may influence salary, like age, education, work classification (KZAM) and region, where an employer works. Women labour market condition goes before the own analysis.

This thesis deals with the measurement of tax evasion. The first part deals with the theory of tax evasion, its general, legislative and economic definition and its consequences. A special subsection is devoted to relation of the tax evasion and the shadow economy. The second part deals with the theory of tax evasion measurement and the last chapter focuses on shadow economy volume measurement and tax evasion measurement in the Czech Republic.

The dissertation deals with the interplay of fiscal and monetary policy in face of uncertainty about the estimation of the true output gap. Theoretical framework of the dissertation set this interplay of monetary and fiscal policy into the realm of game theory, in particularly non-cooperative games of the Nash and Stackelberg equilibrium, respectively. The theoretical framework continued with a description of various methods used for estimation of potential output and output gap, with a special emphasis on methods used in both the Czech National Bank and Czech Ministry of Finance. In the applied part of the dissertation, I studied the interplay of monetary and fiscal policy in the case of Czech economy facing an uncertainty about the estimation of the true output gap. I studied the impact of this interplay on major macroeconomic variables and I tried to determine, which of these two policies plays the role of a leader and which plays the role of a follower in the case of Czech economic environment.

Land surface albedo describes the proportion of incident solar radiant flux that is reflected from the Earth's surface and therefore is a crucial parameter in modeling and monitoring attempts to capture the current climate, hydrological, and biogeochemical cycles and predict future scenarios. Due to the temporal variability and spatial heterogeneity of land surface albedo, remote sensing offers the only realistic method of monitoring albedo on a global scale. While the distribution of bright, highly reflective surfaces (clouds, snow, deserts) govern the vast majority of the fluctuation, variations in the intrinsic surface albedo due to natural and human disturbances such as urban development, fire, pests, harvesting, grazing, flooding, and erosion, as well as the natural seasonal rhythm of vegetation phenology, play a significant role as well. The development of times series of global snow-free and cloud-free albedo from remotely sensed observations over the past decade and a half offers a unique opportunity to monitor and assess the impact of these alterations to the Earth's land surface. By utilizing multiple satellite records from the MODerate-resolution Imaging Spectroradiometer (MODIS), the Multi-angle Imaging Spectroradiometer (MISR) and the Visible Infrared Imaging Radiometer Suite (VIIRS) instruments, and developing innovative spectral conversion coefficients and temporal gap-filling strategies, it has been possible to utilize the strengths of the various sensors to improve the spatial and temporal coverage of global land surface albedo retrievals. The availability of these products is particularly important in tropical regions where cloud cover obscures the forest for significant periods. In the Amazon, field ecologists have noted that some areas of the forest ecosystem respond rapidly with foliage growth at the beginning of the dry season, when sunlight can finally penetrate fully to the surface and have suggested this phenomenon can continue until reductions in water availability (particularly in times of drought) impact the growth cycle. While it has been difficult to capture this variability from individual optical satellite sensors, the temporally gap-filled albedo products developed during this research are used in a case study to monitor the Amazon during the dry season and identify the extent of these regions of foliage growth.

Magister Philosophiae - MPhil / Task based language instruction has generated some debate among researchers. Some argue in favour of task based language instruction by claiming that tasks focus learners' attention on meaning and thus facilitate second language acquisition (Prahbu, 1987; Pica and Doughty, 1986; Pica, Kanagy, and Falodun,1993). Others argue against task based language instruction and call into question the concept of comprehensible input, the idea upon which the whole task based approach is based (Sheen, 1994).

Thesis advisor: Peter Ireland / Retirees with limited financial resources face numerous risks, including out-living their money (longevity risk), investment losses (market risk), unexpected health expenses (health risk), the unforeseen needs of family members (family risk), and even retirement benefit cuts (policy risk). This study systematically values and ranks the financial impacts of these risks from both the objective and subjective perspectives and then compares them to show the gaps between retirees’ actual risks and their perceptions of the risks in a unified framework. It finds that 1) under the empirical analysis, the greatest risk is longevity risk, followed by health risk; 2) under the subjective analysis, retirees perceive market risk as the highest-ranking risk due to their exaggeration of market volatility; and 3) the longevity risk and health risk are valued less in the subjective ranking than in the objective ranking, because retirees underestimate their life spans and their health costs in late life. / Thesis (PhD) — Boston College, 2020. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Economics.

Striatal oscillatory activity associated with movement, reward, and decision-making is observed in several interacting frequency bands. Rodent striatal local field potential recordings show dopamine- and reward-dependent transitions between a 'spontaneous' state involving beta (15-30 Hz) and low gamma (40-60 Hz) and a 'dopaminergic' state involving theta (4-8 Hz) and high gamma (60-100 Hz) activity. The mechanisms underlying these rhythmic dynamics and their functional consequences are not well understood. In this thesis, I construct a biophysical model of striatal microcircuits that comprehensively describes the generation and interaction of these rhythms as well as their modulation by dopamine and rhythmic inputs, and test its predictions using human electroencephalography (EEG) data. Chapter 1 describes the striatal model and its dopaminergic modulation. Building on previous work suggesting striatal projection neuron (SPN) networks can generate beta oscillations, I construct a model network of striatal fast-spiking interneurons (FSIs) capable of generating delta/theta (2-6 Hz) and gamma rhythms. This FSI network produces low gamma oscillations under low (simulated) dopaminergic tone, and high gamma activity nested within a delta/theta oscillation under high dopaminergic tone. In a combined model under high dopaminergic tone SPN network beta oscillations are interrupted by delta/theta-periodic bursts of gamma-frequency FSI inhibition. This high dopamine-induced periodic inhibition may enable switching between beta-rhythmic SPN cell assemblies representing motor programs, suggesting that dopamine facilitates movement in part by allowing for rapid, periodic changes in motor program execution. Chapter 2 describes the model's response to square-wave periodic cortical inputs. Comparing models with and without FSIs reveals that the FSI network: (i) prevents the SPN network's generation of phase-locked beta oscillations in response to beta's harmonic frequencies, ensuring fidelity of transmission of cortical beta rhythms; and (ii) limits or entrains SPN activity in response to certain gamma frequency inputs. Chapter 3 describes an analysis of phase-amplitude coupling at cortical electrodes in human EEG data during a reward task. The alternating rhythms predicted by the model appear in response to positive feedback. While the origins of these rhythms remain unclear, if they represent striatal signals, they provide a direct link between human behavior and striatal cellular function.