The financial crisis of 2007-2009 led to a large increase in the government debt of all advanced economies. In the United States, the debt burden reached levels not seen since the Second World War. In Europe, high fiscal stress evolved into a sovereign debt crisis. My thesis focuses on debt dynamics in advanced economies and the design of policies that can stabilize their fiscal burden. In the first chapter, I provide new evidence and theory on US debt dynamics and their relation with long-term growth forecasts. In the second chapter, I document a novel dataset on the maturity structure of sovereign debt of Euro Area (EA) countries and study the effect of the maturity composition on debt dynamics. Finally, in the third chapter, I analyze empirically the role of debt management in stabilizing the fiscal burden of countries in the EA.<p><p>Chapter 1: Sovereign Debt in the US and Growth Expectations<p><p>This chapter studies the effect of changes in expectations of long-term GDP growth on US government debt and deficits. Long-term growth expectations are an essential determinant of expected future revenue growth and fiscal solvency. I present evidence that US government debt and deficits are positively correlated with long-term GDP (and revenue) growth forecasts from the Congressional Budget Office between 1984 and 2012. This is robust to controlling for current growth and to using à-la-Kalman estimated forecasts for a longer time span. This stylized fact is novel in the macroeconomics literature and I develop a new model of government behavior that explains it.<p>My model features endogenous (forward-looking) purchasing behavior for the government. This distinguishes my model from standard macro theories that assume exogenous government purchases, or ad-hoc backward looking policy rules for government purchases. It builds on the recent ‘long-run risks’ literature by assuming shocks to the trend growth rate of total factor productivity. The model matches the observed positive correlation between fiscal deficits and the trend growth rate, based on the government’s desire to smooth public consumption over periods of higher (or lower) long-run productivity growth. <p><p>Chapter 2: Government Debt Maturity and Debt Dynamics in EA Countries<p><p>This chapter presents a new comprehensive database on sovereign debt stocks and yields, at all maturities, for six EA countries: Belgium, Finland, France, Germany, Italy and Spain between 1991 and 2013. I constructed this database by combining information from different sources (treasuries, national central banks and statistical offices), on a security-by-security basis. A recent literature has shown the importance of debt maturity management in the US - e.g. Hall and Sargent (2011) - however, due to lack of data, this key issue remained unstudied for the EA. Thus, I use my database to study the effect of debt maturity management on the evolution of government debt in EA countries. <p>My main finding is that debt maturity also had an important effect in debt dynamics of the EA. The debt maturity structure affects debt dynamics because longer maturity shields the government budget from changes in interest rates. In general, interest rates in the EA have fallen since 1991 while treasuries in the region extended debt maturity. Thus, an increasing number of long-term bondholders experienced large capital gains. Counterfactual simulations show the impact of a different maturity structure on the evolution of debt and suggest that extending debt maturity in 2014 and 2015 would result in lower debt ratios by 2022. I also estimate the debt-to-GDP erosion induced by higher current and future inflation and find that inflation would lower the fiscal burden in EA countries much more than in the US.<p><p>Chapter 3: Quantifying the Role of Debt Management for Fiscal Self-Insurance in the EA<p><p>The last chapter provides evidence of debt management being an effective tool for protecting the government budget from fiscal spending shocks in the EA. In particular, I document that sovereign bonds of EA countries had a significantly lower real return in response to government spending shocks between 1991 and 2013. Importantly, longer bond maturity generally implied a larger drop in returns. This is in line with theories claiming that long-term debt provides fiscal self-insurance. However, my finding suggests that medium-term debt is more effective in hedging against spending shocks. <p>I identify government spending shocks in a Structural VAR model estimated with both aggregated quarterly fiscal data for the EA and stacked data from individual countries. I also use a simple FAVAR model to distinguish between common and idiosyncratic (country-specific) shocks and document that the former risk was hedged more effectively. The introduction of the Euro reduced the absorption of idiosyncratic shocks (relative to common shocks) by bond returns. However, the European debt crisis brought the degree of fiscal self-insurance against country-specific shocks back to pre-Euro levels. Finally, debt maturity seems to play a minor role in the absorption of country-specific shocks by the return on sovereign bonds. <p> / Doctorat en Sciences économiques et de gestion / info:eu-repo/semantics/nonPublished

In this thesis, I undertake an empirical search for the existence of price and exchange rate bubbles during the inter-war European hyperinflations of Germany, Hungary and Poland. Since the choice of an appropriate policy to control inflation depends upon the true nature of the underlying process generating the inflation, the existence or non-existence of inflationary bubbles has important policy implications. If bubbles do exist, positive action will be required to counter the public's self-fulfilling expectation of a price surge. Hyperinflationary episodes have been chosen as my case study because of the dominant role that such expectations play in price determination. In the literature, there are frequently expressed concerns about empirical research into bubbles. The existence of model misspecification and the nonlinear dynamics in the fundamentals under conditions of regime switching may lead to spurious conclusions concerning the existence of bubbles. Furthermore, some stochastic bubbles may display different collapsing properties and consequently appear to be linearly stationary. Thus, the evidence against the existence of bubbles may not be reliable. In my thesis, I attempt to tackle the above empirical problems of testing for the existence of bubbles using advances in testing procedures and methodologies. Since the number of bubble solutions is infinite in the rational expectations framework, I adopt indirect tests, rather than direct tests, for the empirical study. From the findings of my empirical research, the evidence for stationary specification errors and the nonlinearity of the data series cannot be rejected, but the evidence for the existence of price and exchange rate bubbles is rejected for all the countries under study. It leads to the conclusion that the control of the inter-war European hyperinflations was attributable to control of the fundamental processes, since the dynamics of prices and exchange rates for these countries might not be driven by self-fulfilling expectations.

This thesis deals with the realization of inflation targeting in the Slovak and the Czech Republic, and compares successfulness in fulfilling of inflation target. It is divided into three chapters. The first chapter characterizes monetary policy in general and two transmission mechanisms used in both countries. The next chapter is concerned with the practical application of monetary transmission mechanism after the monetary separation. Problems connected with the realization of this monetary policy regime that led to the change in the transmission mechanism in both central banks are also mentioned. In the last chapter there is the comparison of conditions in Slovakia and the Czech Republic during the implementation and application inflation targeting. We also compare trend in the actual and target inflation rate, and describe changes in the key interest rates of both national banks as a result of it.

Thesis (Ph.D. (Statistics)) -- University of Limpopo, 2022 / Using the ARFIMA (autoregressive and fractionally integrated moving aver age) model extended with sGARCH (standard generalised autoregressive con ditional heteroscedasticity) and ’gjrGARCH (Glosten-Jagannathan-Runkle gen eralised autoregressive conditional heteroscedascity) innovations, fractional in tegration approach and state space model, this study has empirically examined persistency of inflation dynamics of Ghana and South Africa, the only two coun tries in Sub-Saharan Africa with Inflation Targeting (IT) monetary policy. The first part of the analysis employed monthly CPI (Consumer Price Index) in flation series for the period January 1971 to October 2014 obtained from the Bank of Ghana (BoG), and for the period January 1995 to December 2014 ob tained from Statistics South Africa. The second part involves the estimation of threshold effect of inflation on economic growth using annual data obtained from the IMF (International Monetary Fund) database for the period 1981 to 2014, for both countries. Results from the study showed that structural breaks, long memory and non linearities (or regime shifts) are largely responsible for inflation persistence, hence the ever-changing nature of inflation rates of Ghana and South Africa. ARFIMA(3,0.35,1)-‘gjrGARCH(1,1) under Generalised Error Distribution (GED) and ARFIMA(3,0.50,1)-‘gjrGARCH(1,1) under Student-t Distribution (STD) mod els provided the best fit for persistence in the conditional mean (or level) of CPI for Ghana and South Africa, respectively. The results from these models pro vided evidence of time-varying conditional mean and volatility in CPI inflation rates of both countries. The two models also revealed an asymmetric effect of inflationary shocks, where negative shocks appear to have greater impact than positive shocks, in terms of persistence on the conditional mean with time varying volatility. This thesis proposes a model that combines fractional integration with non linear deterministic terms based on the Chebyshev polynomials in time for the analysis of CPI inflation rates of Ghana and South Africa. We tested for non-linear deterministic terms in the context of fractional integration and esti mated the fractional differencing parameters, d to be 1.11 and 1.32 respectively, for the Ghanaian and the South African inflation rates, but the non-linear trends were found to be statistically insignificant in the two series. New ev idence from this thesis depicts that inflation rate of Ghana is highly persistent and non-mean reverting, with an estimated fractional differencing parameter, d > 1.0, and will therefore require some policy action to steer inflation back to stability. However, the South African inflation series was found to be a cyclical process with an order of integration estimated to be d = 0.7, depicting mean reversion, with the length of the cycles approximated to last for 80 months. Finally, the thesis incorporated structural breaks, long memory, non-linearity, and some explanatory variables into a state space model and estimated the threshold effect of inflation on economic growth. The empirical results suggest that inflation below the estimated levels of 9% and 6% for Ghana and South Africa respectively, will be conducive for economic growth. The policy implications of these results for both countries are as follows. First, both series had similar properties responsible for inducing inflation persistence such as structural breaks, non-linearities, long memory and asymmetric re sponse to negatives shocks - but with varied degrees of magnitude. For both countries, the conditional mean and unobserved components such as volatility for both countries were found to be time-varying. This thesis, therefore, recom mends to the BoG and the South African Reserve Bank (SARB) - responsible for monetary policies, and the Finance Ministers of both governments - respon sible for fiscal policies, to take the above-mentioned properties into account in the formulation of their monetary policies. Second, the thesis recommends that the BoG and the SARB consolidate the IT policy, since keeping inflation below the targets set of 9% and 6%, respectively for Ghana and South Africa, will boost economic growth. Third, policymakers could also design measures (monetary and fiscal policies) such as increase in interest rates, credit control, and reduction of unnecessary expenditure, among others, to control inflation due to its adverse effects on market volatility. Even though an increase in interest rates could assist in curtailing the recent and anticipated increase in inflation rates in both countries, where targets have been missed by Ghana and South Africa, it will also be prudent to legislate monetary policies around demand-supply side since the problem of both coun tries appears to be more of a structuralist than a monetarist. It is, therefore, recommended that both countries tighten the IT monetary policy in order to re duce inflation persistence. This will eventually impact on poverty and income distribution with ramifications for economic growth and/or development. The fourth implication of these results is that governments and central banks should be mindful of the actions and decisions they take, in the sense that unguarded decisions and unnecessary alarms could raise uncertainties in the economy, which could, in turn, affect the future trajectory of inflation. Finally, the thesis recommends that governments of both countries strengthen the pri vate sector, which is the engine of growth. For small and open economies such as Ghana and South Africa, this will grow the economy through job creation and restore investor confidence. / National Research Foundation (NRF), Department of Science and Technology (DST), Telkom’s Tertiary Education Support Programme (TESP) and the NRF-DST Centre of Excellence for Mathematical and Statistical Sciences (CoE-MaSS)

It is of great clinical importance to predict the behaviour of the cornea in various diseases and post-surgical recovery. Therefore, a numerical model that is able to simulate the corneal behaviour, considering corneal material properties obtained from individuals is highly desirable. In this work a combined numerical-experimental technique has been developed that can characterize the mechanical properties of a cornea properties from two aspects: time-dependency and spatial variation. Initially, an analysis of the material properties of porcine corneas was performed to investigate the time-dependent behaviour of the cornea. A simple stress relaxation test was used to determine the viscoelastic properties of a cornea and a rheological model was built based on the Generalized Maxwell (GM) approach. A validation experiment using nano-indentation showed that an isotropic GM model was insufficient for describing the corneal time-dependent behaviour when exposed to a complex stress state. A technique was proposed that takes into account the microstructural composition of the cornea and is based on a combination of nano-indentation experiment, isotropic and transversely isotropic numerical models, and an inverse finite element method. The good agreement using this method suggests that this is a promising technique for measuring the time-dependent properties of the cornea. The spatial variation of the properties was then investigated. This time, the long term structural response of the cornea was targeted. A full field displacement response of a loaded cornea was evaluated from Optical Coherence Tomography (OCT) volume reconstructions of the cornea using Digital Volume Correlation (DVC). The inverse finite element method was employed with two models sequentially; first, a radially partitioned model and then a circumferentially partitioned model, in order to recover the elastic parameters in radial and circumferential directions. The good agreement using this method suggests that this is a promising and reliable technique for identifying the distribution of the corneal properties. In this research, we have shown that it is possible to determine the local time-dependent properties of the cornea and the in-depth (2D) distribution of the properties using the hybrid technique. This technique has the potential to be implemented in vivo. However, further work should focus on the feasibility of this technique in practice.

Gravitational waves are truly transparent to matter in the Universe and carry the information of the very early epoch. We show that the energy density spectrum of the primordial gravitational waves has characteristic features due to the successive changes in the relativistic degrees of freedom during the radiation era. Our calculations are solely based on the standard model of cosmology and particle physics, and therefore these features must exist. Our calculations significantly improve the previous ones which ignored these effects and predicted a smooth, featureless spectrum. Going back in time to the beginning of the radiation era, reheating of the Universe must have taken place after inflation for primordial nucleosynthesis to begin. We show that reheating occurs spontaneously in a broad class of inflation models with [scientific symbols] gravity (Ø is inflaton). The model does not require explicit couplings between Ø and bosonic or fermionic matter fields. The couplings arise spontaneously when Ø settles in the vacuum expectation value (vev) and oscillates. This mechanism allows inflaton quanta to decay into any fields which are not conformally invariant in [scientific symbols] gravity theories. Applying the above method, we study implications of the large-N species solution to the hierarchy problem, proposed by G. Dvali, for reheating after inflation. We show that, in this scenario, the decay rates of inflaton fields through gravitational decay channels are enhanced by a factor of N, and thus they decay into N species of the quantum fields very efficiently. Without violating energy conservation, cosmological consideration places non-trivial constraints on Dvali's solution to the hierarchy problem. Going back in time still further, we study the period just before the beginning of reheating, the era of coherent oscillation of scalar fields. We show that non-Gaussian primordial curvature perturbations appear temporarily in the coherent oscillation phase after multi-field inflation. We directly solve the evolution equation of non-Gaussianity on super-horizon scales caused by the non-linear influence of entropy perturbations on the curvature perturbations during this phase. We show that our approach precisely matches with the so-called "separate universe approach" or "δN formalism" by studying a simple quadratic two-field potential. / text

One of the exciting aspects of cosmology is to understand the period of `cosmic inflation' that powered the epoch of the Big Bang. Inflation has been very successful in explaining several puzzles of the standard big bang scenario. But the most important success of inflation is that it can explain the temperature fluctuations of cosmic microwave background and the large scale structures of the universe. Despite its great success, the details of the physics of inflation are still unknown. A large number of models of inflation successfully explain all the observations making it remarkably hard to distinguish between different models. We explore the possibility of differentiating between different inflationary models by studying two-point and three-point functions of primordial fluctuations produced during inflation. First, we explore possible constraints on the inflationary equation state by considering current measurements of the power spectrum. Next, we explore the possibility of a single field slow-roll inflationary model with general initial state for primordial fluctuations. The two-point and three-point functions of primordial fluctuations are generally computed assuming that the fluctuations are initially in the Bunch-Davies state. However, we show that the constraints on the initial state from observed power spectrum and local bispectrum are relatively weak and for slow-roll inflation a large number of initial states are consistent with the current observations. As the precision of the observations is increasing significantly, we may learn more about the initial state of the fluctuations in the near future. Finally, we explore the consistency relations for the three-point functions, in the squeezed limit, of scalar and tensor perturbations in single-field inflation that in principle can be used to differentiate between single-field and multi-field inflation models. However, for slow-roll inflation, we find that it is possible to violate some of the consistency relations for initial states that are related to the Bunch-Davies state by Bogoliubov transformations and we identify the reason for the violation. Then we discuss the observational implications of this violation. / text

International trade theory emphasizes the "real"factors. In standard models of international trade surveyed by Jones and Neary (1984), factor supplies play a key role in determining trade patterns. The pattern as well as the volume of trade is usually explained by the defference in comparative advantages. Through trade, countries can exploit these advantages and make more efficient use of resources. The determination of exchange rates is seen as the resoult of monetary policies in different countries. The distinction between trade and finace has been mitigated due to an important paper by Stockman (1985) who integrate a transactionsbased model of money with a real trade model. He analyzed the effect of inflation on international trade using a cash-in-adcance(CIA) model. In his setup, inflation depresses capital accumulation because the rate of return on investment is reduced. This"factor-supply"effect will cause the volume of trade to change. Since Stockman used a Heckscher- Ohlin-Samuelson model, it also follows that a small change in the rate of inflation may cause a dramatic change in domestic production, hence, the pattern of trade might be reversed completely. In this dessertation I shall point out another channel of how inflation affects the trade pattern and volume. I shall study the "demand-substitution"effect due the fact that the cash-in-advance constraint is applied to different sets of goods. When this is so, the CIA constraint impliesa higher opportunity cost of purchasing the constrained goods. Thus, the relative costs of goods under constraint in terms of the goods not under constraint will be subject to the influence of inflation, this is what I mean by "demand-substitution" effect. This dissertation is organized as follows. In section II we will survey the related literature. In section III we describe the model and the five different CIA constraints case, analyze the effect of unanticipated, anticipated and temporary monetary policy. In every case, comparative static exercise are performed. In section IV we make comparison between the three cases, followed by concluding remarks and possible extensions.

Colorectal polyp prevention trials (PPTs) are randomized, placebo-controlled clinical trials that evaluate some chemo-preventive agent and include participants who will be followed for at least 3 years to compare the recurrence rates (counts) of adenomas. A large proportion of zero counts will likely be observed in both groups at the end of the observation period. Poisson general linear models (GLMs) are usually employed for estimation of recurrence in PPTs. Other models, including the negative binomial (NB2), zero-inflated Poisson (ZIP), and zero-inflated negative binomial (ZINB) may be better suited to handle zero-inflation or other forms of overdispersion that are common in count data. A model selection paradigm that determines a statistical approach for choosing the best fitting model for recurrence data is described. An example using a subset from a large Phase III clinical trial indicated that the ZINB model was the best fitting model for the data.

Jonas Kiselis, Kainų stabilumo užtikrinimas esant fiksuotam valiutos kursui [Rankraštis]: bakalauro baigiamasis darbas: economika. Vilnius, ISM Vadybos ir ekonomikos universitetas, 2009. Šis darbas apie kainų stabilumo užtikrinimą ir infliacijos problemas, iškylančias valstybėms, palaikančioms fiksuotą savo nacionalinės valiutos kursą kitos inkaro valiutos atžvilgiu. Darbe analizuojama dviejų ekonominių regionų ekonominė padėtis šiuo aspektu: Baltijos šalių ir Įlankos Bendradarbiavimo Tarybos. Šie du regionai palyginami, išnagrinėjama, ką jie turi bendro ir kuo skiriasi savo ekonomikų specifika. Pirmoje dalyje analizuojama esama situacija praėjusio laikotarpio kontekste, analizuojamos pagrindinės priežastys, labiausiai lemiančios kainų nestabilumą ir infliacijos lygį Baltijos ir ĮBT ekonominių regionų šalyse. Bandomos pasverti teigiamos ir neigiamos fiksuoto šių valstybių valiutų kursų pasėkmės jų ekonomikoms. Antrojoje dalyje iš teorinės pusės apžvelgiama kainų stabilumo ir infliacijos problematika ekonomikose, kurių valiutos susietos su „inkaru“ (kitos valstybės valiuta arba valiutų krepšeliu). Aiškinamasi, kokių priemonių turi būti imamasi siekiant išlaikyti stabilų kainų lygį ir žemą infliaciją valstybėje, palaikančioje fiksuotą savo nacionalinės valiutos kursą ir apskritai, kokiais atvejais valstybei verta rinktis fiksuotą, o kokiais plaukiojantį valiutos kurso mechanizmą. Trečioje dalyje atliekamas tyrimas, kuriame, naudojantis tiesine regresine analize, bandoma... [toliau žr. visą tekstą] / Jonas Kiselis, Prices Stability Issue Under Fixed Exchange Rate [Rankraštis]: bakalauro baigiamasis darbas: economics. Vilnius, ISM Vadybos ir ekonomikos universitetas, 2009. This paperwork is aimed at analysing prices stability and infliation issues arising in economies of countries with fixed exchange rate. Two economic regions‘ economic states are being analysed from attitude of abovementioned issue. These are Baltic states and Gulf Cooperation Council. These two regions are compared, analysed what is general and different by characteristics of their economies. The first part is dedicated to current situation analysis in context of the past periods of time. The prevailing reasons of prices instability and inflation in the Baltics and GCC are analysed. Both positive and negative consequences of fixed exchange rate are evaluated in these economies. In the second part, prices stability and inflationary issues are reviewed in a country with economy of fixed exchange rate regime, whose currency is pegged to „anchor“ (currency of another country or a basket of currencies). What remedies need to be taken as an instrument of an economic policy in order to manage sustainable prices stability and low inflation rate in the country of fixed exchange rate. What are the cases when a country has to choose fixed exchange rate and what are the cases for a floating exchange rate regime as an optimal option. A research is conducted in the third part of this work. Linear regression analyses... [to full text]