Inaug.-diss--Frankfurt a.M. / Lebenslauf. "Literatur": p. 109-110.

Thesis (D. Mus. Arts)--University of Washington, 2006. / Includes bibliographical references (leaves 94-99).

Proefschrift Universiteit Maastricht. / Auteursnaam op omslag: Peter Berends. Met lit. opg. - Met samenvatting in het Nederlands.

Texte refondu de: Diss.--Amsterdam, 1951. Titre de soutenance : De periodisering der geschiedenis. / Bibliogr. p. 841-928. Index.

Th. Ph. D.--economy--London. / Bibliogr. p. 170-172.

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Botryococcus braunii Bot-22 a été cultivée dans un photobioréacteur plat dans des conditions photoautotrophiques continues. Deux densités de flux de photons (PFD) de 50 et 500 μmol quanta m-2 s-1, deux taux de dilution de 0.178 et 0.357 d-1, trois concentrations différentes d'oxygène dissous et deux périodes de exposition à la lumière ont été appliquées pour produire de différentes productions de biomasse et 'd'hydrocarbures et de profil d’acides gras. L'augmentation de dix fois du PAR-PFD appliqué sur la surface du photobioréacteur induit une augmentation transitoire du rEX, avant d'atteindre un nouvel état stationnaire correspondant à une productivité de la biomasse de 21.34 g m-2 d-1, qui représente une augmentation de 360 % par rapport à la productivité obtenu sous 50 μmol quanta m-2 s-1. En revanche, aucun changement apparent de rEX n'a été observé après avoir doublé le taux de dilution à PFD constant et cela malgré une double augmentation de la productivité de la biomasse jusqu'à 47.8 g m-2 d-1. La productivité des hydrocarbures extracellulaires a suivi la même tendance que les celle de biomasse, atteignant une valeur maximale de 12.4 g m-2 d-1 pour un rendement estimé de la biomasse sur l'apport lumineux de 1.1 g mol de photons-1. La productivité d'hydrocarbures la plus élevée correspondait aux photons continus, une dilution de 0.357 d-1, 500 μmol quanta m-2 s-1 et à 4 % de la concentration d'oxygène dissous. Les principaux acides gras du «B. braunii race B strain BOT-22 fatty acids » étaient l'acide oléique, l'acide palmitique, l'acide a-linoléique, et l'acide stéarique. / Botryococcus braunii Bot-22 was cultivated in a flat-panel photobioreactor under continuous photoautotrophic conditions. Two photon flux densities (PFD) of 50 and 500 μmol photons m-2 s-1, two dilution rates of 0.178 and 0.357 d-1, three different dissolved oxygen concentration and two light periods were applied to provide different biomass and hydrocarbon production and fatty acids profile. The tenfold increase of the PAR-PFD applied on the photobioreactor surface induced a transient increase of rEX, before reaching a new steady state corresponding to a biomass productivity of 21.34 g m-2 d-1, a 360 % increase as compared to the productivity obtained under 50 μmol photons m-2 s-1. By contrast, no apparent change of rEX was observed after doubling the dilution rate at constant PFD, despite a twofold increase of the biomass productivity, up to 47.8 g m-2 d-1. The extracellular hydrocarbons productivity followed the same trend as the biomass data, reaching a maximal value of 12.4 g m-2 d-1 for an estimated biomass yield on light supply of 1.1 g mol photons-1. The highest hydrocarbon productivity was corresponding to continuous light, dilution rate of 0.357d-1, 500 μmol photons m-2 s-1 and 4 % of dissolved oxygen concentration. The main fatty acids of B. braunii race B strain BOT-22 fatty acids were, oleic acid, palmitic acid, a-linoleic acid, and stearic acid.

>Magister Scientiae - MSc / Methamphetamine (MA), also known as ‘Tik’, has detrimental short- and long-term psychological and morphological effects on the central nervous system (CNS). The lipophilic nature of MA allows it to cross the blood-brain barrier (BBB) which normally plays a protective role in limiting solute exchange (including narcotics) into the neuronal tissue. Numerous studies have indicated that MA not only crosses the BBB but is implicated in distorting its crucial role in that it increases the permeability of the endothelial cells and thereby compromises its core homeostatic function. The speculated mechanism by which MA elicits its effects involves elevated ROS production which may be reversed by antioxidant treatment. Rooibos herbal tea (Aspalathus linearis) which is well documented for its antioxidative properties and ROS scavenging abilities may therefore be the ideal candidate to reverse the harmful ROS-induced effects of MA. The aim of the study was to investigate the in vitro ameliorating potential of fermented rooibos (Rf) against the MA-induced effects on mouse brain endothelial (bEnd5) cells by utilizing various assays (trypan blue exclusion and XTT viability assays) and physiological parameters (cell numbers, viability, monolayer permeability and cell cycle phases) over a period of 96 hrs. Statistical analysis was performed using the Wilcoxon rank sum test with P<0.05 denoted as significant. Once-off exposure to physiological MA concentrations and Rf resulted in % viability similar to controls by 96 hrs with suppression observed only when the cells were exposed to daily MA (0.1-1000 μM) (P≤0.0063). Exposure to supraphysiological concentrations (≥100 μM) of MA greatly suppressed viability (P≤0.0463). Both daily and once-off treatment to the combinations initially resulted in increased viability however by 96 hrs was similar to- or exceeding the controls (P≤0.0180). MA exposure also resulted in decreased live cell numbers (P≤0.0339) with no effect when exposed to Rf by 96 hrs. The combinations resulted in cell numbers comparable to controls. Dose-dependent increases in electrical resistance were observed in response to singular MA and Rf treatment with lower MA concentrations displaying significant decreases (P≤0.0064). Similar trends were observed with combinations however greater resistance was observed. Increased G1-phase populations (P≤0.0495) in response to singular MA and Rf exposure was noted followed by decreased S-phase fractions (P≤0.0356). While MA decreased G2-M phase cells (P≤0.0498) it was unaffected by Rf. In contrast, the combination of MA and Rf decreased events in the G1-phase (P≤0.0483), with an increased S-phase population (P≤0.0415). In conclusion, the single compounds displayed mirroring effects, decreasing the cells’ permeability and causing G1-phase arrest. The modulatory effects of Rf in combination with MA was illustrated with the restoration of viability and live cell numbers comparable to that of controls, and a more restrictive monolayer as well as reversal of the G1-phase arrest. Findings suggest that Rf may reverse the adverse effects of MA on the BBB.

Thesis advisor: Ryan Chahrour / The dissertation studies the sources of business cycles taking both an open and a closed economy perspective. A common feature of the two chapters composing the dissertation is the use of simple, but powerful classifications and identifications of sources of business cycles. In particular, the first chapter, titled “What are the Sources of Boom-Bust Cycles?”, concerns the distinction between economic fluctuations due to changes in beliefs, and fluctuations due to changes in fundamentals, showing results that challenge traditional approaches to modeling business cycles. The second chapter, titled “Shocks and Exchange Rates in Small Open Economies”, takes the perspective of small open economies, and concerns the distinc- tion between global and domestic shocks, showing results that are informative for a series of puzzling facts concerning the dynamics of the exchange rate. In “What are the Sources of Boom-Bust Cycles?,” joint with Marco Brianti, we provide a synthesis of two major views on economic fluctuations. One view maintains that expansions and recessions arise from the interchange of positive and negative persistent exogenous shocks to fundamentals. This is the conventional view that gave rise to the profusion of shocks used in modern dynamic stochastic general equilibrium models. In contrast, a second view, which we call the endogenous cycles view, holds that business cycle fluctuations are due to forces that are internal to the economy and that endogenously favor recurrent periods of boom followed by a bust. In this environment, cycles can occur after small perturba- tions of the long run equilibrium. We find empirical evidence pointing at the coexistence of both views. In particular, we find that the cyclical behaviour of economic aggregates is due in part to strong internal mechanisms that generate boom-bust phenomena in response to small changes in expectations, and in part to the interchange of positive and negative persistent fundamental shocks. Motivated by our findings, we build a theory that unifies the dominant paradigm with the endogenous cycles approach. Our theory suggests that recessions and expansions are intimately related phenomena, and that understanding the nature of an expansion, whether it is driven by fundamentals or by beliefs, is a first order issue for policy makers whose mandate is to limit the occurrance of inefficient economic fluctuations. In “Shocks and Exchange Rates in Small Open Economies,” joint with Pierre De Leo, we propose a novel approach to separately identify domestic and external shocks in small open economies. Our results provide guidance about the transmission mechanism of these shocks and revisit recent conclusions drawn on the exchange rate effects of monetary policy in small open economies. The identification method is based on the premise that shocks originating from within a small economy should not influence world variables at any horizon, while external (or global) shocks should affect world variables at least at some horizon. We obtain three empirically related findings. First, external shocks feature large deviations from uncovered interest parity, while domestic shocks do not. Second, external shocks strongly comove with global risk aversion and U.S. macroeconomic variables. Third, recent puzzling estimates of the exchange rate effects of monetary policy stem from an identification of domestic shocks that fails to properly account for international spillovers. We show that a two-country small open economy model with international asset market imperfections is consistent with these facts. In our proposed model, global risk aversion shocks drive exchange rate dynamics, and a country’s net foreign asset position governs their international transmission. We provide empirical evidence that a country’s exposure to external shocks indeed depends on its net foreign asset position. / Thesis (PhD) — Boston College, 2020. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Economics.

This dissertation combines micro-level empirical analyses and general equilibrium structural models to study shock propagation mechanisms and business cycles dynamics, with a particular emphasis on the role played by firms. In the first chapter, we study how regional shocks spill over across U.S. local markets through intra-firm market networks and explore how such spillovers reshape household welfare across regions. We link data on barcode-region-level prices and quantities with producer-level information to exploit variation in firms' initial exposure to differential drops in local house prices in the 2007-09 recession. We show that a firm's local sales decrease in response to not only direct negative local demand shock but also indirect negative local demand shocks originating in its other markets. Intra-firm cross-market spillover effects arise mainly from product creation and destruction, whereas direct local shock operates through the sales of continuing products. Spillover effects occur because (i) firms replace products that have higher value---sales per product, unit price, and organic sales share---with lower-value ones in response to negative demand shocks, and (ii) such product replacements are synchronized across many markets within each firm. Counterfactual analysis using an estimated multi-region model with endogenous quality adjustments shows that our channel works as a novel inter-regional shock transmission mechanism and generates an implicit regional redistribution effect. Such effect is economically sizable and is comparable to the size of transfer policies implemented during the Great Recession. In the second chapter, we investigate a role of supply chain network in transmitting housing market disruptions during the Great Recession. We build up a unique micro-level data that combines local housing market condition, firms' sales in each local market, and firm-level supply chain network information. Exploiting firm-specific demand shock stemming from cross-market variation in house price changes and an initial difference in firms' local sales, we find that such shock not only affects downstream firms but also transmits to their suppliers. The estimated supplier-level elasticity is quantitatively large, reflecting larger role of downstream firms with higher elasticity in the network structure. To quantify such propagation at the aggregate level, we build up a parsimonious network model calibrated to match the micro-level data. Our counterfactual analysis shows that approximately 18\% of the observed drop in the aggregate output can be attributed to the propagating role of the supply chain network. In the third chapter, we study the business cycle with a Translog production function. We empirically identify a complementarity between labor and energy that leads to procyclical returns to scale, which is not compatible with the tightly parameterized production function commonly used in the literature (Cobb-Douglas and CES). Therefore, we propose a flexible Translog production function that not only features complementarity-induced procyclical returns to scale but is also consistent with a balanced growth path. A simple calibrated business cycle model with the proposed production function generates strikingly data-consistent dynamics following demand shocks without relying on either nominal rigidities or countercyclical markups.