The medieval climate anomaly and Byzantium: a review of the evidence on climatic fluctuations, economic performance and societal change

At the beginning of the Medieval Climate Anomaly, in the ninth and tenth century, the medieval eastern Roman empire, more usually known as Byzantium, was recovering from its early medieval crisis and experiencing favourable climatic conditions for the agricultural and demographic growth. Although in the Balkans and Anatolia such favourable climate conditions were prevalent during the eleventh century, parts of the imperial territories were facing significant challenges as a result of external political/military pressure. The apogee of medieval Byzantine socio-economic development, around AD 1150, coincides with a period of adverse climatic conditions for its economy, so it becomes obvious that the winter dryness and high climate variability at this time did not hinder Byzantine society and economy from achieving that level of expansion. Soon after this peak, towards the end of the twelfth century, the populations of the Byzantine world were experiencing unusual climatic conditions with marked dryness and cooler phases. The weakened Byzantine socio-political system must have contributed to the events leading to the fall of Constantinople in AD 1204 and the sack of the city. The final collapse of the Byzantine political control over western Anatolia took place half century later, thus contemporaneous with the strong cooling effect after a tropical volcanic eruption in AD 1257. We suggest that, regardless of a range of other influential factors, climate change was also an important contributing factor to the socio-economic changes that took place in Byzantium during the Medieval Climate Anomaly. Crucially, therefore, while the relatively sophisticated and complex Byzantine society was certainly influenced by climatic conditions, and while it nevertheless displayed a significant degree of resilience, external pressures as well as tensions within the Byzantine society more broadly contributed to an increasing vulnerability in respect of climate impacts. Our interdisciplinary analysis is based on all available sources of information on the climate and society of Byzantium, that is textual (documentary), archaeological, environmental, climate and climate model-based evidence about the nature and extent of climate variability in the eastern Mediterranean. The key challenge was, therefore, to assess the relative influence to be ascribed to climate variability and change on the one hand, and on the other to the anthropogenic factors in the evolution of Byzantine state and society (such as invasions, changes in international or regional market demand and patterns of production and consumption, etc.). The focus of this interdisciplinary

STABILITY ANALYSIS WITH APPLICATIONS OF A TWO-DIMENSIONAL DYNAMICAL SYSTEM ARISING FROM A STOCHASTIC MODEL FOR AN ASSET MARKET

We analyze the stability properties of equilibrium solutions and periodicity of orbits in a two-dimensional dynamical system whose orbits mimic the evolution of the price of an asset and the excess demand for that asset. The construction of the system is grounded upon a heterogeneous interacting agent model for a single risky asset market. An advantage of this construction procedure is that the resulting dynamical system becomes a macroscopic market model which mirrors the market quantities and qualities that would typically be taken into account solely at the microscopic level of modeling. The system`s parameters correspond to: (a) the proportion of speculators in a market; (b) the traders` speculative trend; (c) the degree of heterogeneity of idiosyncratic evaluations of the market agents with respect to the asset`s fundamental value; and (d) the strength of the feedback of the population excess demand on the asset price update increment. This correspondence allows us to employ our results in order to infer plausible causes for the emergence of price and demand fluctuations in a real asset market. The employment of dynamical systems for studying evolution of stochastic models of socio-economic phenomena is quite usual in the area of heterogeneous interacting agent models. However, in the vast majority of the cases present in the literature, these dynamical systems are one-dimensional. Our work is among the few in the area that construct and study analytically a two-dimensional dynamical system and apply it for explanation of socio-economic phenomena.

Short-time behaviour of demand and price viewed through an exactly solvable model for heterogeneous interacting market agents

We introduce a stochastic heterogeneous interacting-agent model for the short-time non-equilibrium evolution of excess demand and price in a stylized asset market. We consider a combination of social interaction within peer groups and individually heterogeneous fundamentalist trading decisions which take into account the market price and the perceived fundamental value of the asset. The resulting excess demand is coupled to the market price. Rigorous analysis reveals that this feedback may lead to price oscillations, a single bounce, or monotonic price behaviour. The model is a rare example of an analytically tractable interacting-agent model which allows LIS to deduce in detail the origin of these different collective patterns. For a natural choice of initial distribution, the results are independent of the graph structure that models the peer network of agents whose decisions influence each other. (C) 2009 Elsevier B.V. All rights reserved.

New maritime transport scenarios. Part II: fluctuations in shipping and new scenarios

This FAL Bulletin details the situation of the shipping industry and forms the second and final part of a larger document that begins with Issue No. 338, which puts the current status of maritime trade in context. Both documents fit into a series of bulletins about ports and maritime trade in the region and are, therefore, closely linked to Issue No. 337, which sets out the need for a new port governance in the region to address the new circumstances that have arisen in the maritime market.

Sources of fluctuations in parallel exchange rates and policy reform in Myanmar

Myanmar maintained a multiple exchange rate system, and the parallel market exchange rate was left untamed. In the last two decades, the Myanmar kyat exchange rate of the parallel market has exhibited the sharpest fluctuations among Southeast Asian currencies in real terms. Since the move to a managed float regime in April 2012, the question arises of whether exchange rate policies will be effective in stabilizing the real exchange rate. This paper investigates the sources of fluctuations in the real effective exchange rate using Blanchard and Quah’s (1989) structural vector autoregression model. As nominal shocks can be created by exchange rate policies, a persistent impact of a nominal shock implies more room for exchange rate policies. Decomposition of the fluctuations into nominal and real shocks indicates that the impact of nominal shocks is small and quickly diminishes, implying that complementary sterilization is necessary for effective foreign exchange market interventions.

Impacts of foreign exchange auctions on the informal market rate in Myanmar

Since the abolition of the official peg and the introduction of a managed float in April 2012, the Central Bank of Myanmar has operated the daily two–way auctions of foreign exchange aimed at smoothing exchange rate fluctuations. Despite the reforms to the foreign exchange regime, however, informal trading of foreign exchange remains pervasive. Using the daily informal exchange rate and Central Bank auction data, this study examines the impacts of auctions on the informal market rate. First, a VAR analysis indicates that the official rate did not Granger cause the informal rate. Second, GARCH models indicate that the auctions did not reduce the conditional variance of the informal rate returns. Overall, the auctions have only a quite modest impact on the informal exchange rate.

The tug of war. Russia's response to changes on the European gas market. OSW Study 50/2014

Russia, being aware of the evolution of the EU gas market and the fluctuations in trends that accompany it, and in an attempt to maintain its position on the European gas market, is sticking to a dichotomous strategy. On the one hand, Moscow has taken an offensive approach: it continues its traditionally critical rhetoric with regard to the legal and institutional changes; by negating the legitimacy of the new rules, it has been making efforts to undermine them by employing legal and political measures; Russia has used such traditional economic means as investments in assets and pushing through the implementation of new gas pipeline construction projects. On the other hand, the evolution of the EU gas market has forced Russia to take steps to adapt to a certain extent: partial changes in the operation of the internal gas sector; promises to further curb Gazprom’s dominant position; the concessions made in trade negotiations with European partners; partial adjustments to the EU’s so called third energy package regulations. Hoping that the unfolding situation on the gas markets will contribute to slowing down the recent liberalisation tendencies in the EU and that EU member states won’t make progress in decreasing their dependence on Russian gas, Moscow is thus preparing itself for the ‘long game’ in gas with its European partners.

Hand in hand:privatising five star hotels in Egypt through the stock market will enhance the latter's role as well as set an example of the benefits that could be gained from privatisation

This thesis examines the possibility of privatising public owned five star hotels in Egypt through its stock market in order to give a boost to the Egyptian privatisation programme and to help activate its stock market. To explore these aspects, two main technical exercises were executed. First the writer constructed, for the first time in Egypt, a daily price index for Cairo Stock Exchange and an index for the tourism sector, in order to analyze the efficiency of the capital market. This technical analysis showed that Cairo stock exchange is inefficient, stagnant and undergoes minimal fluctuations, especially when compared to other developed and emerging markets. Second, given the importance and complexity of the valuation of SOEs prior to their privatisation, a sample of three five star hotels that could be prime candidates for privatisation via the stock market in Egypt were selected and a detailed financial analysis for the three hotels was concluded. The result was a valuation range for the three hotels using various valuation methods. Nevertheless it was found out that the final value of hotels will be determined by the market itself. Depite the inefficiency of Cairo Stock Exchange, the thesis did not rule out privatisation through the stock market. On the contrary it cited several examples of developing countries that were able to successfully privatise some of their SOEs via their rudimentary capital markets. Finally, the thesis recommended that five star hotels could be pefect candidates for privatisation via the stock market in Egypt. This is because five star hotels are profitable, privately managed, non strategic and not highly capital intensive businesses. In addition, they do not suffer from overstaffing and the industry in which they operate i.e. tourism sector, has high growth prospects and is of an international nature. Therefore it is anticipated that privatisation of five star hotels can attract a lot of investors because of the relatively high returns. This in turn will help activate and popularize the capital market in Egypt. At the same time the benefits of privatisation would be more visible which will give more momentum to the privatisation programme and make it more politically acceptable.

Hiánygazdaság - többletgazdaság. Tanulmány a piac elméletéről - I. rész = Shortage economy surplus economy. A study on market theory I

A főáramlat közgazdászai elismerik, hogy a szocialista rendszert a krónikus hiány jellemezte, de úgy vélik, hogy a kapitalista rendszerben - kisebb vagy nagyobb ingadozások közepette - piaci egyensúly uralkodik. Ezzel szemben a tanulmány két piaci állapotot állít egymással szembe. Az egyikben dominálnak a túlkeresleti jelenségek, bár előfordulnak túlkínálati jelenségek is, ezt nevezi a szerző hiánygazdaságnak. A másikban dominálnak a túlkínálati jelenségek, bár előfordulnak túlkeresleti jelenségek is, amit a szerző többletgazdaságnak nevez. A hiánygazdaságot magyarázó tényezőket a szerző korábbi munkái írták le. A jelen tanulmány I. része azokat a mechanizmusokat mutatja be, amelyek a kapitalizmus keretei között létrehozzák a többletgazdaságot: a korlátozott verseny, a schumpeteri "teremtő rombolás", a vállalat törekvése biztonsági tartalékok kiépítésére és a növekvő skálahozadék. Foglalkozik azokkal a jelenségekkel, amelyek fékezik a kereslet és az árak alkalmazkodását. Külön fejezet tárgyalja a többlet mérésének (és ezzel szoros összefüggésben a fogalmak szigorú definícióinak) nehézségeit. ______ Mainstream economists recognize that the socialist system was marked by chronic shortage, but they consider that the capitalist system exhibits market equilibrium, give or take some greater or lesser fluctuations. This study, however, contrasts two market states. One is dominated by phenomena of excess demand, though instances of excess supply appear as well; this the author calls a shortage economy. The other is dominated by phenomena of excess supply, though instances of excess demand appear as well; this the author terms a surplus economy. The author has described in earlier works the factors explaining the shortage economy. Part I of the study presents the mechanisms generating a surplus economy under capitalism: imperfect competition, Schumpeterian "creative destruction" , the efforts of firms to build up safety reserves, and increasing economies of scale. It also covers phenomena that curb accommodation of demand and prices. Discussed in a separate chapter are the difficulties of measuring surplus (and closely tied with this, of strictly defining the concepts).

Hiánygazdaság − többletgazdaság. Tanulmány a piac elméletéről – II. rész = Shortage economy - surplus economy. A study on market theory II

A főáramlat közgazdászai elismerik, hogy a szocialista rendszert a krónikus hiány jellemezte, de úgy vélik, hogy a kapitalista rendszerben - kisebb vagy nagyobb ingadozások közepette - piaci egyensúly uralkodik. Ezzel szemben a tanulmány két piaci állapotot állít egymással szembe. Az egyikben dominálnak a túlkeresleti jelenségek, bár előfordulnak túlkínálati jelenségek is, ezt nevezi a szerző hiánygazdaságnak. A másikban dominálnak a túlkínálati jelenségek, bár előfordulnak túlkeresleti jelenségek is, amit a szerző többletgazdaságnak nevez. A tanulmány II. része összefoglalja a tanulmány fő állításait. Ezek szerint a szocialista rendszer veleszületett immanens tulajdonsága a hiánygazdaság, míg a kapitalista rendszer veleszületett immanens tulajdonsága a többletgazdaság létrehozása és állandó reprodukciója. Állami beavatkozások erősíthetik vagy gyengíthetik ezeket a genetikus tulajdonságokat, de nem szüntethetik meg. A tanulmány áttekinti a többletgazdaság kedvező és kedvezőtlen hatásait. A kedvező hatások között különleges nyomatékkal emeli ki, hogy a többlet (elsősorban többletkapacitások) nélkül nem alakulhat ki a termelők, illetve az eladók rivalizálása, ami az innovációs folyamat legfontosabb hajtóereje. A többletgazdaság általános esetének vizsgálata után különböző speciális esetekkel foglalkozik a tanulmány: a gazdaság konjunkturális hullámzásával, a hadigazdasággal, a modern kapitalizmusban mutatkozó történelmi léptékű változásokkal, valamint a szocialista rendszeren belül megjelent piacorientált reformokkal és a posztszocialista átmenettel. ____ Mainstream economists recognize that the socialist system was marked by chronic shortage, but they consider that the capitalist system exhibits market equilibrium, give or take some greater or lesser fluctuations. This study, however, contrasts two market states. One is dominated by phenomena of excess demand, though instances of excess supply appear as well; this the author calls a shortage economy. The other is dominated by phenomena of excess supply, though instances of excess demand appear as well; this the author terms a surplus economy. Part II of the study starts by summing up its main propositions. Just as the shortage economy is an intrinsic, immanent trait of the socialist system, so the creation and continual reproduction of the surplus economy is an intrinsic, immanent trait of the capitalist system. Such genetic traits may be strengthened or weakened by state intervention, but not eliminated by it. The study reviews the favourable and detrimental effects of the surplus economy. Of the favourable effects, it is emphasized that without surplus there cannot develop among producers or sellers the rivalry that provides the main impetus for the innovation process. Having examined the general case of the surplus economy, the study turns to various special cases: to the trade-cycle fluctuations of the economy, the war economy, the historic changes appearing in modern capitalism, the market-oriented reforms that appear within the socialist system, and the post-socialist transition.

Essays on Job Search and Labor Market Dynamics

This dissertation consists of three separate essays on job search and labor market dynamics. In the first essay, “The Impact of Labor Market Conditions on Job Creation: Evidence from Firm Level Data”, I study how much changes in labor market conditions reduce employment fluctuations over the business cycle. Changes in labor market conditions make hiring more expensive during expansions and cheaper during recessions, creating counter-cyclical incentives for job creation. I estimate firm level elasticities of labor demand with respect to changes in labor market conditions, considering two margins: changes in labor market tightness and changes in wages. Using employer-employee matched data from Brazil, I find that all firms are more sensitive to changes in wages rather than labor market tightness, and there is substantial heterogeneity in labor demand elasticity across regions. Based on these results, I demonstrate that changes in labor market conditions reduce the variance of employment growth over the business cycle by 20% in a median region, and this effect is equally driven by changes along each margin. Moreover, I show that the magnitude of the effect of labor market conditions on employment growth can be significantly affected by economic policy. In particular, I document that the rapid growth of the national minimum wages in Brazil in 1997-2010 amplified the impact of the change in labor market conditions during local expansions and diminished this impact during local recessions.

In the second essay, “A Framework for Estimating Persistence of Local Labor

Demand Shocks”, I propose a decomposition which allows me to study the persistence of local labor demand shocks. Persistence of labor demand shocks varies across industries, and the incidence of shocks in a region depends on the regional industrial composition. As a result, less diverse regions are more likely to experience deeper shocks, but not necessarily more long lasting shocks. Building on this idea, I propose a decomposition of local labor demand shocks into idiosyncratic location shocks and nationwide industry shocks and estimate the variance and the persistence of these shocks using the Quarterly Census of Employment and Wages (QCEW) in 1990-2013.

In the third essay, “Conditional Choice Probability Estimation of Continuous- Time Job Search Models”, co-authored with Peter Arcidiacono and Arnaud Maurel, we propose a novel, computationally feasible method of estimating non-stationary job search models. Non-stationary job search models arise in many applications, where policy change can be anticipated by the workers. The most prominent example of such policy is the expiration of unemployment benefits. However, estimating these models still poses a considerable computational challenge, because of the need to solve a differential equation numerically at each step of the optimization routine. We overcome this challenge by adopting conditional choice probability methods, widely used in dynamic discrete choice literature, to job search models and show how the hazard rate out of unemployment and the distribution of the accepted wages, which can be estimated in many datasets, can be used to infer the value of unemployment. We demonstrate how to apply our method by analyzing the effect of the unemployment benefit expiration on duration of unemployment using the data from the Survey of Income and Program Participation (SIPP) in 1996-2007.

Econometric models in foreign exchange market

According to the significance of the econometric models in foreign exchange market, the purpose of this research is to give a closer examination on some important issues in this area. The research covers exchange rate pass-through into import prices, liquidity risk and expected returns in the currency market, and the common risk factors in currency markets. Firstly, with the significant of the exchange rate pass-through in financial economics, the first empirical chapter studies on the degree of exchange rate pass-through into import in emerging economies and developed countries in panel evidences for comparison covering the time period of 1970-2009. The pooled mean group estimation (PMGE) is used for the estimation to investigate the short run coefficients and error variance. In general, the results present that the import prices are affected positively, though incompletely, by the exchange rate. Secondly, the following study addresses the question whether there is a relationship between cross-sectional differences in foreign exchange returns and the sensitivities of the returns to fluctuations in liquidity, known as liquidity beta, by using a unique dataset of weekly order flow. Finally, the last study is in keeping with the study of Lustig, Roussanov and Verdelhan (2011), which shows that the large co-movement among exchange rates of different currencies can explain a risk-based view of exchange rate determination. The exploration on identifying a slope factor in exchange rate changes is brought up. The study initially constructs monthly portfolios of currencies, which are sorted on the basis of their forward discounts. The lowest interest rate currencies are contained in the first portfolio and the highest interest rate currencies are in the last. The results performs that portfolios with higher forward discounts incline to contain higher real interest rates in overall by considering the first portfolio and the last portfolio though the fluctuation occurs.

An Analysis of Colombian Power Market Price Behavior from an Industrial Organization Perspective

We analyze the behavior of spot prices in the Colombian wholesale power market, using a series of models derived from industrial organization theory -- We first create a Cournot-based model that simulates the strategic behavior of the market-leader power generators, which we use to estimate two industrial organization variables, the Index of Residual Demand and the Herfindahl-Hirschman Index (HHI) -- We use these variables to create VAR models that estimate spot prices and power market impulse-response relationships -- The results from these models show that hydroelectric generators can use their water storage capability strategically to affect off-peak prices primarily, while the thermal generators can manage their capacity strategically to affect on-peak prices -- In addition, shocks to the Index of Residual Capacity and to the HHI cause spot price fluctuations, which can be interpreted as the generators´ strategic response to these shocks

Bipolar Tribocharging Signal During Friction Force Fluctuations At Metal-insulator Interfaces.

Friction and triboelectrification of materials show a strong correlation during sliding contacts. Friction force fluctuations are always accompanied by two tribocharging events at metal-insulator [e.g., polytetrafluoroethylene (PTFE)] interfaces: injection of charged species from the metal into PTFE followed by the flow of charges from PTFE to the metal surface. Adhesion maps that were obtained by atomic force microscopy (AFM) show that the region of contact increases the pull-off force from 10 to 150 nN, reflecting on a resilient electrostatic adhesion between PTFE and the metallic surface. The reported results suggest that friction and triboelectrification have a common origin that must be associated with the occurrence of strong electrostatic interactions at the interface.

Beam-energy and system-size dependence of dynamical net charge fluctuations

We present measurements of net charge fluctuations in Au+Au collisions at s(NN)=19.6, 62.4, 130, and 200 GeV, Cu+Cu collisions at s(NN)=62.4 and 200 GeV, and p+p collisions at s=200 GeV using the dynamical net charge fluctuations measure nu(+-,dyn). We observe that the dynamical fluctuations are nonzero at all energies and exhibit a modest dependence on beam energy. A weak system size dependence is also observed. We examine the collision centrality dependence of the net charge fluctuations and find that dynamical net charge fluctuations violate 1/N(ch) scaling but display approximate 1/N(part) scaling. We also study the azimuthal and rapidity dependence of the net charge correlation strength and observe strong dependence on the azimuthal angular range and pseudorapidity widths integrated to measure the correlation.