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Lower and Upper Bounds for Maximum Number of RunsYang, Qian January 2007 (has links)
<p> A string is a sequence of various simple elements. The most straightforward examples of strings are English words-concatenations of the 26 letters of the English alphabet. A repetition in a string x is a nonempty substring of the form x[i..j] = u^k, k ≥ 2. The study of repetitions in strings is as old as the study of strings themselves. Furthermore, the identification of repetitions in a given finite string still remains an important topic in a variety of contexts: pattern-matching, computational biology, data compression, cryptology, and many other areas. </p> <p> A run in a string xis a substring in the form x[i..j] = u^kv, k ≥ 2 where v is a prefix of u, u is not a repetition itself, and this substring x[i..j] is neither left-extendible nor right-extendible. The notion of runs thus captures the notion of leftmost maximal repetitions and allows for a succinct notation [M89]. The maximal number of runs over all strings of length n is denoted as p(n). To determine the properties of the function p(n) is an important aspect of the research in periodicities in strings. </p> <p> Prior to the asymptotic lower bound presented by Franek and myself in [FY06] (presented here in Chapter 2), there had been no known non-trivial lower bound for p(n), asymptotic or otherwise. A result suggesting a possible lower bound was presented by Franek, Simpson and Smyth in 2003, introducing a construction of a sequence of strings {xn}~=0, so that limn→∞ r(Xn)/[Xn] = 3/(1+√5) ≈ 0.927 [FSS03]. Theirmethod was extended to provide a true asymptotic lower bound in [FY06]. In the first part of Chapter 2, the recursive construction of the sequence of strings from [FSS03] is presented with all details not discussed in either [FSS03] or [FY06]. In the second part of Chapter 2, a construction of the lower bound is presented with all details. This part represents my original contribution to the research. </p> <p> I designed a new approach to generate strings that are "rich in runs" other then the one used in [FSS03] and [FY06]. A similar approach as in Chapter 2 is used to construct a lower bound for p(n) using the alternate construction of sequences of strings. This new construction method gives, interestingly, sequences with the same limit as in [FY06], thus giving some support to the conjecture that limn→∞ p(n)/n = 3/(1+√5) stated in [FSS03]. This method is presented in Chapter 3. The whole Chapter 3 thus represents another part of my original contribution to the research. </p> <p> It had been known since the 1980's that the number of repetitions in a string of length n is at most of the order O(n log n). A remarkable result by Kolpakov and Kucherov in 2000 showed that p(n) was in fact bounded by a function linear in n [KK00]. Their approach only. provided the existence of such a function, not the concrete values of its constants. Recently, Rytter improved the upper bound of p(n) to 5n. [R06). The paper by Rytter was published in a conference proceedings and as such lacked many details in some areas and was bit too vague. In Chapter 4 I present Rytter's proof with all relevant details filled in. Through a private communication I learned at the time of writing of this thesis that the upper bound had been improved by Rytter, and independently by Smyth, Simpson, and Puglisi to 3.5n. The latest upper bound is supposed to be now as low as 1.5n. However, none of the upper bounds better than 5n has been published yet. </p> <p> In the last chapter I discuss my conclusions and point out the directions for the future research. </p> / Thesis / Master of Science (MSc)
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Estimation of Bank Runs probability in the context of Deposit Insurance implementation in RussiaDănilă, Ecaterina January 2013 (has links)
This thesis empirically investigates the bank runs probability cases over the period 2005-2011 on Russian banking market and, simultaneously, tests the hypothesis of influence of bank-fundamental factors and macroeconomic conditions on the decision of depositors to withdraw their funds from banks. Methodologically, was conducted a logit econometric model to test our assumptions. We find evidence on both bank- fundamentals, such as high debt ratio, rising real interest rates, small asset size, and macroeconomic conditions, such as high inflation, and sharp increases in the real exchange rates, to influence on bank runs. In addition, the thesis analyzes the significance of deposit insurance implementation in avoiding bank runs. Moreover, we compare if the newly adopted deposit insurance diminished the credibility of the depositors in the state-controlled banks compared with private banks, thus, increasing the amount of investments to private banks. Finally, based on our approach, the method identifies a run on Russian deposit market during quarter four of 2008 year; however we would not characterize it as a severe run because it did not touch all banks but more as a partial one (approx. 1/3 of banks from the system were affected).
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The Study of Corporate Social Responsibility in ChinaChi, Tzu-ling 12 June 2009 (has links)
In nowadays, the corporate social responsibility (CSR) plays one kind of social function. The corporate social responsibility means that the corporations use their resources to satisfy all the related people and the morals. Coming to 21st century, people start to request corporations to do more except their professional activities with high CSR standards.
After 1949, mainland China (People Republic of China) run planned economic system and didn¡¦t allow any private economies. China government set up state-owned enterprises to produce and distributed all commodities. The state-owned enterprises had to undertake not only the commercial economic responsibility but also the social responsibility. The state-owned enterprise had to take care all the employees¡¦ families from birth to death. After the economic reform, private corporations and transnational enterprises developed rapidly. But like other developing country expanded their economy, people don¡¦t pay attention to CSR until they were aware their living environments were destroyed. The domestic corporations started to do something for the employees, customers, environment, and public welfare.
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Three Essays on Monetary and Financial EconomicsXu, Xun Unknown Date
No description available.
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Genome scan for homozygosity islands and inbreeding effect on reproductive traits in nelore beef cattle / Detecção de ilhas em homozigose e efeito da endogamia sobre características reprodutivas em bovinos neloreHerrera Rios, Ana Cristina 30 July 2018 (has links)
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Previous issue date: 2018-07-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O uso intensivo de biotecnologias reprodutivas tem feito com que se eleve a taxa de nascimento de progênies com maior grau de parentesco (maior taxa de nascimento de meio-irmãos e irmãos completos). Assim, o conhecimento sobre o coeficiente da endogamia média do rebanho torna-se relevante para a eficiência do sistema de produção. Com o advento da genômica, o coeficiente de endogamia (F) pode ser estimado com base na informação de milhares de marcadores do tipo polimorfismos de base única (SNPs), espalhados por todo o genoma. No presente estudo, informações de 3.785 animais da raça Nelore (1,760 machos e 2,025 fêmeas) genotipados para 777.962 SNPs do BovineHD BeadChip (Illumina Inc., San Diego, CA, USA) foram utilizadas com o objetivo de avaliar a taxa de endogamia em rebanhos comerciais da raça Nelore, bem como investigar o seu efeito (depressão endogâmica) sobre a expressão fenotípica de características reprodutivas (idade ao primeiro parto (IPP), ocorrência de prenhez precoce (OPP) e reconcepcão de novilhas (REC)). A estimativa do valor de F, bem como da depressão endogâmica, foi feita utilizando diferentes metodologias: (i) matriz de parentesco genômica com frequências alélicas obtidas da população base (FG); (ii) matriz de parentesco genômica com frequências alélicas fixadas em 0,5 (FGRM); (iii) com base no excesso de SNPs em homozigose (FSNP); e (iv) corrida de homosigose (FROH). Os resultados da corrida de homosigose também foram utilizados para identificar os padrões (tamanho e distribuição) dos segmentos ROH na raça Nelore bem como para identificar ilhas de homosigose (segmentos ROH compartilhados por mais de 50% da população). Foram identificados 210.636 segmentos ROH distribuídos nos 29 autossomos e cinco ilhas de homozigose localizadas nos cromossomos 5, 7, 12, 21 e 26, nas quais 43 genes foram identificados. Alguns destes genes (INHBE, INHBC, STAT6, FGF8 e DPCD) foram previamente associados com caracteristicas reproductivas, de crescimento, resposta inmume e adaptabilidade em bovinos. As médias para o coeficiente de endogamia calculado com base nas diferentes abordagens foram: -0,0006 (FG), 0,4376 (FGRM), 0,5500 (FSNP) e 0,0590 (FROH). As correlações foram ente baixas FG-FSNP (-0,28), FG-FGRM (-0,20), FG-FROH (0,21), a moderadas FROH-FSNP (0,68), FROH-FGRM (0,72) e fortemente alta para FSNP-FGRM (0,99). O valor médio de F variou de acordo com a metodologia utilizada. O valor extremamente alto do FSNP denota que este método tende a superestimar as taxas de endogamia. Independentemente do método utilizado para obter os valores de F, foi verificado que o aumento de 1% no coeficiente de endogamia médio do rebanho influenciou desfavoravelmente a média das características reprodutivas avaliadas. / The intensive use of reproductive biotechnologies has increased the birth rate of progenies with high degree of relationships (higher birth rate of half- and full-sibs). Thus, the control of herd inbreeding becomes relevant for the efficiency of the production system. With genomics, the inbreeding coefficient can be estimated using thousands of single nucleotide polymorphisms (SNPs), spread throughout the genome. In the present study, information of 3,785 Nelore animals (1,760 males and 2,025 females) genotyped with 777,962 SNP markers of BovineHD BeadChip (Illumina Inc., San Diego, CA, USA) was used with the objective of evaluating the inbreeding rates of Nelore commercial herds, as well as to investigate the effects of inbreeding (inbreeding depression) on the phenotypic expression of reproductive traits (age at first calving (AFC), heifer early pregnancy (EP), and heifer rebreeding (HR)). The inbreeding coefficient (F) and inbreeding depression were estimated based on (i) genomic relationship matrix considering allele frequencies estimated from the base population (FG); (ii) genomic relationship matrix considering allele frequencies fixed at 0.5 (FGRM); (iii) excess of homozygous SNPs (FSNP); and (iv) runs of homozygosity (FROH). The runs of homozygosity results were also used to identify the pattern (size and distribution) of ROH segments as well as to identify ROH islands (ROH segments shared by more than 50% of the population). In total, there were identified 210,636 ROH segments and five ROH Islands located on the chromosomes 5, 7, 12, 21 and 26, in which 43 annotated genes were identified. Some of these genes (INHBE, INHBC, STAT6, FGF8 and DPCD) were previously associated with reproduction and growth traits, inmume response and adaptability in cattle. The average inbreeding calculated based on different approaches were -0.0006 (FG), 0.4376 (FGRM), 0.5500 (FSNP) e 0.0590 (FROH). These correlations ranged from low FG-FSNP (-0.28), FG-FGRM (-0.20), FG-FROH (0.21), to moderated FROH-FSNP (0.68), FROH-FGRM (0.72) and extremely high FSNP-FGRM (0.99). The average population inbreeding coefficient ranged according to the method used. The extremely high value of FSNP indicates that this approach tend to overestimate the inbreeding rates. Independently of the method used to obtain the F values, it was verified that the increase of 1% in the average herd inbreeding unfavorably influenced the mean value of the evaluated reproductive traits. / FAPESP#2009/16118-5
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International financial crises, term structure of foreign debt and monetary policy in open economiesCaliskan, Ahmet 16 August 2006 (has links)
In this dissertation, I study international financial crises. For this purpose, I build two models. In the first model, I focus on financial crises in developing, large open economies where foreign debt with various maturities and issue dates is available. The objective is to measure the vulnerability of the domestic financial system to domestically triggered bank runs and externally triggered sudden stops. The main contribution of this model is that both types of crises are treated as rational responses of domestic depositors and international creditors. Such vulnerability measures are linked to fundamentals and equilibrium term structure of foreign debt. Banks vulnerability to runs increases if they hold a relatively shorter term debt. Also, a larger cost of liquidating the long-term investment before maturity makes the banks more fragile. In the next step, given a domestic banking crisis, I allow international creditors to decide whether they want to stop lending to domestic banks (in which case a Âsudden stop takes place) or not. A sudden stop is more likely if (i) creditors highly discount future consumption, (ii) creditors current income is small relative to their future income, and (iii) the cost of liquidating the long-term investment before maturity is small. In the second model, I investigate the merits of alternative monetary policies with respect to financial fragility. In this monetary model of an explicit financial system, I motivate the demand for two fiat currencies by spatial separation and limited communication of agents. There is a domestic and a foreign currency freely traded without restrictions. I analyze the policy of a constant growth rate of domestic money supply with a floating exchange rate regime. Both currencies are held in positive amounts at the steady-state only if the growth rate of domestic money supply is equal to the world inflation rate (WIR). If the former rate is larger than the WIR, domestic currency is not held at the steady-state. Also, total real money balances held is negatively related with WIR. Finally, monetary policy in the form of a constant growth rate of domestic money supply is neutral with respect to welfare.
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Essays on Banking Crises and Deposit InsuranceWang, Wen-Yao 15 May 2009 (has links)
My research focuses on the reasons for banking crises and the corresponding policy rules
that could help prevent such crises. This abstract briefly reviews the two essays in my
dissertation. The first essay focuses on the optimal mechanism design of the deposit
insurance system while the second essay studies the impact of international illiquidity on
domestic banking crises.
The Recent Deposit Insurance Reform in the U.S. raised the coverage limit for
certain types of deposits. In chapter II, I study the optimal coverage limit in a model of
deposit insurance in the banking system. Because of the coverage limit, depositors have
incentives to monitor the bank’s risk-taking behavior, threatening banks with the
withdrawal of deposits if necessary. The model includes risk-taking banks,
heterogeneous depositors, and a benevolent insurance company providing deposit
insurance. I find that partial coverage combined with risk-sensitive premia in the
presence of capital requirements can improve social welfare and manage banks’ risktaking
behavior. Moreover, when a partial coverage limit is in place, banks are better off
by finding a balance between the higher premia and the depositors’ monitoring and
withdrawals.
Unlike chapter II, chapter III focuses on the role played by international
illiquidity. I build a dynamic general equilibrium model (DGEM) of a small, open
economy. The features I include in the model are nontrivial demands for fiat currencies,
unanticipated sunspots, and financial/banking crises originated by sudden stops of foreign capital inflows are. This chapter gives us a better understanding of the
performance of alternative exchange rate regimes and associated monetary policies
under a simple setup. I show the existence of multiple equilibria that may be ranked
based on the presence of binding information constraints and on welfare. Moreover, I
show that a strong connection of the scope for existence and for indeterminacy of
equilibria with the underlying policy regime. I also find that the presence of binding
multiple reserve requirements help in reducing the scope for financial fragility and panic
equilibria.
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International financial crises, term structure of foreign debt and monetary policy in open economiesCaliskan, Ahmet 16 August 2006 (has links)
In this dissertation, I study international financial crises. For this purpose, I build two models. In the first model, I focus on financial crises in developing, large open economies where foreign debt with various maturities and issue dates is available. The objective is to measure the vulnerability of the domestic financial system to domestically triggered bank runs and externally triggered sudden stops. The main contribution of this model is that both types of crises are treated as rational responses of domestic depositors and international creditors. Such vulnerability measures are linked to fundamentals and equilibrium term structure of foreign debt. Banks vulnerability to runs increases if they hold a relatively shorter term debt. Also, a larger cost of liquidating the long-term investment before maturity makes the banks more fragile. In the next step, given a domestic banking crisis, I allow international creditors to decide whether they want to stop lending to domestic banks (in which case a Âsudden stop takes place) or not. A sudden stop is more likely if (i) creditors highly discount future consumption, (ii) creditors current income is small relative to their future income, and (iii) the cost of liquidating the long-term investment before maturity is small. In the second model, I investigate the merits of alternative monetary policies with respect to financial fragility. In this monetary model of an explicit financial system, I motivate the demand for two fiat currencies by spatial separation and limited communication of agents. There is a domestic and a foreign currency freely traded without restrictions. I analyze the policy of a constant growth rate of domestic money supply with a floating exchange rate regime. Both currencies are held in positive amounts at the steady-state only if the growth rate of domestic money supply is equal to the world inflation rate (WIR). If the former rate is larger than the WIR, domestic currency is not held at the steady-state. Also, total real money balances held is negatively related with WIR. Finally, monetary policy in the form of a constant growth rate of domestic money supply is neutral with respect to welfare.
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Fractionation StatisticsWang, Baoyong 01 May 2014 (has links)
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.
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Essays on international finance and trade policyBaumann, Brittany A. 04 March 2016 (has links)
This dissertation covers both policy-oriented and theory-based topics in International Economics. The first two chapters cover financial policy related to the capital account, while the third chapter covers tariff policy related to the current account.
The first chapter examines the theoretical value of capital controls in reducing the probability of bank runs. I develop a global game model with information-based bank runs and strategic complementarities within and between foreign and domestic creditors. My analysis appears to be the first to model the interconnectedness of foreign and domestic creditor behavior. The framework pins down the probability of a bank run and shows that a capital control can lower the probability of a domestic bank run and of capital flight. I also find that a control on outflows is relatively more effective than a control on inflows. Finally, I test the model's implications using the abnormal returns of Brazilian and South Korean bank stock prices as a proxy for the probability of bank runs.
The second chapter analyzes the policy actions of Brazil and Chile between 2009 and the third quarter of 2011, when Brazil deployed capital account regulations and Chile intervened in its currency markets. I examine the effectiveness of each of these actions and the extent to which the actions of Brazil caused capital flow spillovers in the Chilean market. Consistent with the peer-reviewed literature on the subject, I find that capital account regulations had small but significant effects on the shifting the composition of capital inflows toward longer-term investment, on the level and volatility of the exchange rate, on asset prices, and on the ability of Brazil to have independence in monetary policy. Brazil's regulations did also temporarily cause an increase in capital flows into Chile. Chile's interventions did not have a lasting impact on the Chilean exchange rate or on asset prices beyond the initial announcements of the policies. In Brazil's case we thus conclude that Brazil's regulations helped the nation 'lean against the wind,' but were not enough to tame the 'tsunami' of post-crisis capital flows.
The third chapter uses a computable general equilibrium (CGE) model calibrated to late nineteenth century parameters to show that protectionism alleviated the skilled wage gap. Had the U.S. chosen free trade instead of protective tariffs, wage inequality generally would have been higher in the post-bellum era. The imposition of high tariffs after the Civil War may have dampened what some economic historians believe to have been a long-term upward trend in inequality--the rising portion of the American-Kuznets' curve.
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