The thesis focuses on the interaction between macroprudential and monetary policies in the presence of bank runs. In particular, it is examined whether the two policies should be conducted separately or jointly, and whether the occurence of a bank run affects the result. Furthermore, it is studied how a bank run impacts the efficiency of the two policies. \\ The baseline results suggest that cooperation between the two policies is less efficient than when they are determined separately. The reason might be a coordination issue that arises because the same objective is being assigned to both policies in the cooperative case. On the other hand, when facing a bank run the cooperative regime achieves a higher degree of financial stability by reducing the probability of a next run. This is caused by the fact that cooperating authorities choose more aggresive macroprudential policy when a bank run occurs. A bank run itself does not change the ranking of the two policy regimes. However, an occurence of a bank run induces higher efficiency of both policies, irrespective of the regime in place. In addition, the policies are more effective when they face financial shocks, as opposed to a productivity shock.

Paralog reduction, the loss of duplicate genes after whole genome duplication (WGD) is a pervasive process. Whether this loss proceeds gene by gene or through deletion of multi-gene DNA segments is controversial, as is the question of fractionation bias, namely whether one homeologous chromosome is more vulnerable to gene deletion than the other. As a null hypothesis, we first assume deletion events, on one homeolog only, excise a geometrically distributed number of genes with unknown mean mu, and these events combine to produce deleted runs of length l, distributed approximately as a negative binomial with unknown parameter r; itself a random variable with distribution pi(.). A biologically more realistic model requires deletion events on both homeologs distributed as a truncated geometric. We simulate the distribution of run lengths l in both models, as well as the underlying pi(r), as a function of mu, and show how sampling l allows us to estimate mu. We apply this to data on a total of 15 genomes descended from 6 distinct WGD events and show how to correct the bias towards shorter runs caused by genome rearrangements. Because of the difficulty in deriving pi(.) analytically, we develop a deterministic recurrence to calculate each pi(r) as a function of mu and the proportion of unreduced paralog pairs. This is based on a computing formula containing nested sums. The parameter mu can be estimated based on run lengths of single-copy regions. We then reduce the computing formulae, at least in the one-sided case, to closed form. This virtually eliminates computing time due to highly nested summations. We formulate a continuous version of the fractionation process, deleting line segments of exponentially distributed lengths in analogy to geometric distributed numbers of genes. We derive nested integrals and discover that the number of previously deleted regions to be skipped by a new deletion event is exactly geometrically distributed. We undertook a large simulation experiment to show how to discriminate between the gene-by-gene duplicate deletion model and the deletion of a geometrically distributed number of genes. This revealed the importance of the effects of genome size N, the mean of the geometric distribution, the progress towards completion of the fractionation process, and whether the data are based on runs of deleted genes or undeleted genes.

A bank run occurs when a large number of customers withdraw their deposits from a financial institution at the same time. This can destabilise the bank to the point where it runs out of cash and thus faces sudden bankruptcy. As more people withdraw their deposits, the likelihood of bankruptcy increases, thus triggering further withdrawals. In game theory this type of situation can be modelled as a “coordination game”, that is, a game with two pure equilibria: If sufficiently many people keep their money in the bank, then it will not default and it is rational for everyone to keep their money in the bank. On the other hand, if sufficiently many people withdraw their deposits the bank will default and it is then rational for everyone to try to withdraw their deposits. The overall objective of this study is to explain the phenomenon of bank runs by introducing the Diamond–Dybvig model. This model assumes that the function of a bank is to offer both long-term loans for investments and relatively short-term deposit service. Bank runs comes out as one of two equilibria when too many withdraw early before the long-term loans is paid back. Our task is to find out the condition that can lead to bank runs and more importantly, we will suggest two ways to address the problem of bank runs.

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In 2007 and 2008 more than 100 million dollars of fresh market tomatoes were grown in Virginia, with the majority of production occurring on the Eastern Shore of Virginia (ESV), according to the National Agricultural Statistics Service. Bacterial wilt of tomato, caused by Ralstonia solanacearum (Smith) and Yabucchi et al., is the most devastating disease of tomato on the ESV. Four 'observational trials' were conducted on the ESV over three growing seasons to determine the temporal and spatial distribution of this disease in commercial tomato fields. Plants were assessed at approximately one-week intervals throughout the growing seasons and the incidence of bacterial wilt for each individual plant was recorded. A steady increase in both disease incidence and clustered distribution of the disease within rows was observed as the growing season progressed. Positive correlations between disease incidence and percentage of rows exhibiting a significant clustered distribution occurred in all trials, which indicated an increase in clustered distribution as disease incidence increased. Research trials were conducted over three years, beginning in the summer of 2007, to investigate the effects of tomato bacterial wilt resistant cultivars on the ESV. In 2008 and 2009, the selective, systemic compound which induces host plant resistance, acibenzolar-S-methyl (ASM) was incorporated into resistant cultivar trials. Results from the 2007 trial revealed significant resistance in some of the breeding lines, CRA 66 and PI 126408. The 2008 and 2009 trials revealed that ASM was not effective at reducing levels of bacterial wilt. Grafted transplants in the spring trials of 2008 and 2009 had varied results in resistance and yield. Results revealed the tomato cultivar BHN 669 was an excellent resistant cultivar with promising yield potential and fruit quality. / Master of Science

Endogamy levels are usually estimated using genealogical or molecular markers data. By means of both type of data from a traditional Brazilian tri-hybrid quilombo population aggregate (located at the Ribeira River Valley in the State of São Paulo), the aim of this work, using different methods, was to obtain reliable estimates of its average inbreeding coefficient, as well as to establish pertinent demographic inferences. The results we obtained are presented in three chapters. The first one, represented by the offprint of a published paper, deals with the estimation of the inbreeding coefficient using both a complete genealogical and comprehensive molecular information. F values were estimated for each community using all available pedigree information and averaging the inbreeding coefficients from all individuals represented in the genealogies. Molecular f values were estimated from the analysis of 30 highly heterogenous sets of molecular markers (14 biallelic SNPs and 16 multiallelic microsatellites), genotyped in different groups of individuals from the population. The second chapter (a research paper already published), presents a simplified method to estimate the variance of the inbreeding coefficient. The simple approximations we provided can be applied to a locus with any number of alleles, producing estimates fully validated by computer simulations. The last chapter is a manuscript yet to be published that deals with inbreeding and demographic inferences, obtained from the information of hundreds of thousands of biallelic SNP markers. A new manner to obtain estimates of Wright\'s fixation index f is presented, consisting in the use of the joint information of two sets of markers (one complete and another excluding markers in patent linkage disequilibrium). Quilombo demographic inferences were obtained by means of ROHs analyses, which were adapted to cope with a highly admixed population with a complex foundation history / Os níveis de endogamia de uma população são comumente estimados por meio do coeficiente de endocruzamento, que pode ser obtido de dados genealógicos (F) ou dados provenientes da análise de marcadores moleculares (f). O objetivo do trabalho foi obter estimativas confiáveis do coeficiente de endocruzamento populacional, bem como realizar inferências demográficas, usando dados de um agregado populacional quilombola miscigenado com ancestralidade complexa tri-híbrida, localizado no Vale do Rio Ribeira, na região sul do estado de São Paulo. No trabalho é apresentado em três capítulos. No primeiro (um trabalho já publicado), estimamos o coeficiente de endocruzamento usando dados genealógicos e moleculares. As estimativas genealógicas de F foram obtidas para cada comunidade por meio da média dos coeficientes individuais de todos os indivíduos representados nas genealogias da população. Os valores de f foram estimados por meio dos dados de 30 marcadores moleculares altamente heterogêneos (14 SNPs e 16 microssatélites), genotipados em diferentes grupos de indivíduos com diferentes finalidades. O segundo capítulo, representado por um trabalho também já publicado, apresenta um método simples para estimar a variância do coeficiente de endocruzamento f. As aproximações obtidas, validadas devidamente por simulações em computador, podem ser aplicadas a lóci multialélicos, produzindo estimativas que não diferem significativamente de outras aproximações complicadas descritas na literatura. O último capítulo (um manuscrito a ser submetido para publicação) apresenta inferências a respeito dos processos de endogamia e demografia no isolado quilombola, utilizando a informação de centenas de milhares de marcadores moleculares bialélicos. É apresentada uma nova maneira de se estimar o índice de fixação f de Wright, usando a informação combinada de dois conjuntos de marcadores (o conjunto completo de marcadores e um outro contendo apenas marcadores não ligados significativamente entre si). Também foram feitas inferências sobre a história demográfica do isolado por meio do estudo das regiões genômicas em homozigose (ROHs), uma contribuição inédita e importante do trabalho, adaptada à análise de um isolado populacional altamente miscigenado com contribuição tri-híbrida e uma história de fundação complexa

This study tests for the market efficiency of the Nairobi Securities Exchange (NSE) after the year 2000 to determine the effect of technological advancements on market efficiency. Data that is used is the NSE 20 share index over the period 2001 to 2015; and the NSE All Share Index (NSE ASI) from its initiation during 2008 to 2015. We cannot accept the Efficient Market Hypothesis (EMH) for the NSE using the serial correlation test, the unit root tests and the runs test. However, we can accept the EMH for the more robust variance ratio test. Overall, the results of the market efficiency are mixed. The most significant finding is that the efficiency of the NSE has increased since the year 2000 which suggests that advancements in technology have contributed to the increase in the market efficiency of the NSE. / Business Management / M. Com. (Business Management)

Natural and artificial selection cause changes in certain regions of the genome resulting in selection signatures. Thus, is expected to identify genes associated with the traits under selection in such regions. Selection signatures may be identified using different methodologies, and some are based on detecting of contiguous sequences of homozygous identical-by-descent haplotypes, called runs of homozygosity (ROH), or estimating fixation index (FST) of genomic windows that indicates genetic differentiation. In our study, we aimed to identify selection signatures in a paternal broiler line and to investigate the genes annotated in these regions as well as the biological phenomena involved. For such purpose, ROH and FST-based analysis were performed using whole genome sequence of twenty eight chickens from two different generations. ROH analysis identified homozygous regions of short and moderate length. Analyzing ROH patterns it was observed regions commonly shared among some animals and changes in ROH abundance and length between the two generations. The results also suggests that WGS outperforms SNPchip data, however the number of individuals analyzed must be properly chosen. FST-based analysis revealed genetic differentiation in some genomic windows. Annotation of the consensus regions of ROH and FST windows counted for many genes of which some were previously associated with traits of economic interest, such as APOB, IGF1, IGFBP2, POMC, PPARG, and ZNF423. Overrepresentation analysis of the genes resulted in biological terms of skeletal muscle, matrilin proteins, adipose tissue, hyperglycemia and diabetes, Salmonella infections and tyrosine. Therefore, suggested that ancient and recent selection in TT line acted over regions affecting performance traits. / Identificação de assinaturas de seleção envolvidas com características de desempenho em uma linhagem paterna de frangos de corte Seleção natural e artificial causam mudanças em determinadas regiões do genoma, resultando em assinaturas de seleção. Assim, espera-se identificar genes associados às características sob seleção nessas regiões. Assinaturas de seleção podem ser identificadas usando diferentes metodologias, e algumas delas são baseadas na detecção de sequências contíguas de haplótipos homozigotos idênticos por descendência, chamados segmentos de homozigose (ROH), ou na estimativa do índice de fixação (FST) de janelas genômicas que indicam diferenciação genética. Em nosso estudo, objetivamos identificar assinaturas de seleção em uma linha paterna de frangos de corte e investigar os genes anotados nessas regiões, bem como os fenômenos biológicos envolvidos. Para tal propósito, as análises de ROH e FST foram realizadas usando dados de sequenciamento completo do genoma (WGS) de vinte e oito aves de duas gerações diferentes. A análise de ROH identificou regiões em homozigose de comprimentos curto e moderado. Analisando os padrões de ROH, foram observadas regiões comumente compartilhadas entre alguns animais e mudanças na abundância e no comprimento da ROH entre as duas gerações. Os resultados também sugerem que dados de WGS apresentam vantagens sobre os dados de SNPchip, porém o número de indivíduos analisados deve ser levado em consideração. A análise baseada em FST revelou diferenciação genética em algumas janelas genômicas. Anotação das regiões consenso de ROH e das janelas FST identificaram diversos genes, alguns dos quais já foram associados a características de interesse econômico, como APOB, IGF1, IGFBP2, POMC, PPARG e ZNF423. Análises de enriquecimento dos genes resultaram em termos biológicos de músculo esquelético, proteínas matrilinas, tecido adiposo, hiperglicemia e diabetes, infecções por Salmonella e tirosina. Portanto, sugerimos que a seleção ocorrida durante várias gerações na linha TT atuou sobre as regiões que afetam as características de desempenho destes animais.

Thesis advisor: Susanto Basu / The goal of this dissertation is to shed some light on three separate aspects of the financial system that can lead to greater instability in the banking sector and greater macroeconomic volatility. The starting point of the Great Recession was the collapse of the banking sector in late 2007; in the subsequent months, liquidity evaporated in many markets for short term funding. The process of creating liquidity carried out by the banking system involves the transformation of long term illiquid assets into short term liquid liabilities. This engine functions properly as long as cash lenders continue to roll over short term funding to banks; whenever these lenders fear that banks will not be able to pay back these obligations, they immediately stop funding banks' short term liabilities. This makes banks unable to repay maturing short term debt, which leads to large spikes in default risk. This is often referred to as a modern bank run. Virtually all the theories of bank runs suggest that the severity of a run depends on how well lenders can coordinate their beliefs: whenever a lender expects many others to run, he becomes more likely to run as well. In a joint work with Emanuele Brancati, the first chapter of my dissertation, we empirically document the role of coordination in explaining bank runs and default risk. We establish two new results. First, when information is more precise and agents can better coordinate their actions, a change in market expectations has a larger impact on default risk; this implies that more precise information increases the vulnerability or instability of the banking system. This result has a clear policy implication: if policymakers want to stabilize the banking system they should promote opacity instead of transparency, especially during periods of financial turmoil. Second, we show that when a bank is expected to perform poorly, lower dispersion of beliefs actually increases default risk; this result is in contrast with standard theories in finance and can be rationalized by thinking about the impact that more precise information has on the ability of creditors to coordinate on a bank run. Another aspect of the banking system that is creating a lot of instability in Europe is the so called "disastrous banks-sovereign nexus": many banks in troubled countries owned a disproportionately large amount of domestic sovereign bonds; therefore, in case of a default of the sovereign country, the whole domestic banking sector would incur insurmountable losses. This behavior is puzzling because these banks in troubled countries would greatly benefit from having a more diversified asset portfolio, but instead decide to load up with domestic sovereign debt only. In a joint work with Filippo De Marco, the second chapter of my dissertation, we show that banks receive political pressures from their respective governments to load up on domestic sovereigns. First, we show that banks with a larger fraction of politicians as shareholders display greater home bias. More importantly, we exploit the fact that low-performing banks received liquidity injections by their domestic governments to show that, among those banks, only the "political banks" drastically increased their home bias upon receiving government help. Furthermore, it appears that the extent of political pressure on banks is much stronger on those "political banks" belonging to troubled countries. These findings suggest that troubled countries that would need to pay a high premium to issue new debt force their "political banks" to purchase part of the debt issuance. This greater risk-synchronization can create a dangerous loop of higher sovereign default risk leading to insolvency of the domestic banking system, which in turn would require a bail-out from the local government, further exacerbating the sovereign de- fault risk. Finally, the third chapter of my dissertation, a joint work with Susanto Basu, investigates the sources of excess consumption volatility in emerging markets. It is a well documented fact that, in emerging markets, consumption is more volatile than output whereas the opposite is true in developed economies. We propose an explanation for this phenomenon that relies on a specific form of financial markets incompleteness: we assume that households would always want to front-load consumption and they can borrow from abroad up to a fraction of the value of posted collateral. With the value of collateral being procyclical, households are able to increase borrowing during an expansion and ultimately consume more than they produce; this mechanism is then able to generate a ratio of consumption volatility to output volatility grater than one. Most importantly, the model delivers the implication that a better ability to borrow vis-a-vis the same value of collateral generates greater relative consumption volatility. We then bring this model's implication to the data and find empirical support for it. We proxy the ability to borrow with various measures of effectiveness of lending regulation and more standard indicators of financial development. Consistent with the model's implication, more lending friendly regulation leads to greater relative consumption volatility in emerging markets; moreover, this link breaks down among developed countries. In addition, among emerging countries, it appears that deeper domestic capital markets have a destabilizing effect in terms of greater relative consumption volatility while a more developed domestic banking system does not exerts any such detrimental effect. / Thesis (PhD) — Boston College, 2015. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Economics.