Cross-correlation-aided transport in stochastically driven accretion flows

The origin of linear instability resulting in rotating sheared accretion flows has remained a controversial subject for a long time. While some explanations of such non-normal transient growth of disturbances in the Rayleigh stable limit were available for magnetized accretion flows, similar instabilities in the absence of magnetic perturbations remained unexplained. This dichotomy was resolved in two recent publications by Chattopadhyay and co-workers [Mukhopadhyay and Chattopadhyay, J. Phys. A 46, 035501 (2013)1751-811310.1088/1751-8113/46/3/035501; Nath, Phys. Rev. E 88, 013010 (2013)PLEEE81539-375510.1103/PhysRevE.88.013010] where it was shown that such instabilities, especially for nonmagnetized accretion flows, were introduced through interaction of the inherent stochastic noise in the system (even a "cold" accretion flow at 3000 K is too "hot" in the statistical parlance and is capable of inducing strong thermal modes) with the underlying Taylor-Couette flow profiles. Both studies, however, excluded the additional energy influx (or efflux) that could result from nonzero cross correlation of a noise perturbing the velocity flow, say, with the noise that is driving the vorticity flow (or equivalently the magnetic field and magnetic vorticity flow dynamics). Through the introduction of such a time symmetry violating effect, in this article we show that nonzero noise cross correlations essentially renormalize the strength of temporal correlations. Apart from an overall boost in the energy rate (both for spatial and temporal correlations, and hence in the ensemble averaged energy spectra), this results in mutual competition in growth rates of affected variables often resulting in suppression of oscillating Alfven waves at small times while leading to faster saturations at relatively longer time scales. The effects are seen to be more pronounced with magnetic field fluxes where the noise cross correlation magnifies the strength of the field concerned. Another remarkable feature noted specifically for the autocorrelation functions is the removal of energy degeneracy in the temporal profiles of fast growing non-normal modes leading to faster saturation with minimum oscillations. These results, including those presented in the previous two publications, now convincingly explain subcritical transition to turbulence in the linear limit for all possible situations that could now serve as the benchmark for nonlinear stability studies in Keplerian accretion disks.

Foreign policy in the Grand Coalition

There is a strongly rooted assumption that foreign policy is an executive domain and rarely plays a role in the electoral struggle. Germany is something of an exception and this paper looks at the way foreign policy has provided a site for electoral competition in Germany. Its principal focus is on the two Grand Coalitions with an especial emphasis on the contest between Chancellor Merkel and Foreign Minister Steinmeier to turn foreign policy profile into party advantage. It concludes that this contest was won overwhelmingly by Chancellor Merkel but that in contrast to the first Grand Coalition that foreign policy was not transformative. © 2010 Association for the Study of German Politics.

In memoriam: Dimitar Shishkov

Bulgarian and world computer science lost a prominent colleague: Dimitar Petrov Shishkov 22th January 1939, Varna – 8th March 2004, Sofia D. Shishkov graduated mathematics at Sofia University in 1962. In the last year of his studies he started a specialization as a programmer at the Joint Institute of Nuclear Research – Dubna which lasted three years. Then he worked at the Institute of Mathematics for two years. In 1966 D. Shishkov together with a group of experts transferred to the newly created Central Laboratory for Information Technologies. In 1976 he defended his PhD dissertation. He has been an associate professor in computer science at Sofia University since 1985 and a professor in computer science since 2000. His scientific interests and results were in the fields of computer architectures, computational linguistics, artificial intelligence, numerical methods, data structures, etc. He was remarkable with his teaching activities. D. Shishkov was the creator of high-quality software for the first Bulgarian electronic calculator “ELKA” – one of the first calculators in the world as well as for the series of next calculators and for specialized minicomputers. He was the initiator of the international project “Computerization of the natural languages”. He was a member of a range of international scientific organizations. Among his numerous activities was the organization of the I-st Programming competition in 1979. D. Shishkov was the initiator of sport dancing in Bulgaria (1967) and founder of the first sport-dancing high school education in the world. D. Shishkov was a highly accomplished person with a diversity of interests, with a developed social responsibility and accuracy in his work. In 1996 D. Shishkov was awarded with the International Prize ITHEA for outstanding achievements in the field of Information Theories and Applications. We are grateful to D. Shishkov for the chance to work together with him for establishment and development of IJ ITA.

Strategies for sustaining manufacturing competitiveness:comparative case studies in Australia and Sweden

Purpose - The purpose of this paper is to report an investigation of local sustainable production in Australia and Sweden aimed at exploring the factors contributing to survival and competitiveness of manufacturing companies. Design/methodology/approach - In Australia, six companies were studied in 2010, with comparisons being made with three of them from earlier projects. In Sweden, eight manufacturing companies were studied on two occasions 30 years apart, in 1980 and 2010. To provide a valid comparative perspective a common format for data collection and analysis was used. Findings - There has been a shift in the nature of competition in both Sweden and Australia due to an increasing complexity of the global business environment as well as changes in technology and customer expectations. Despite the differences in country context, the findings suggest that all the manufacturing companies have a good awareness of the elements of the market environment and the relationships with their competitive strategy. However, in general, the Swedish companies have more experience of managing the risks and benefits from operating in the international environment. Research limitations/implications - The results of the research are based on a relatively small sample of case companies in a limited number of industrial sectors. There are methodology implications for future research in the area. Practical implications - The research results have practical implications for the manufacturing industry, especially for companies operating in a competitive international environment. Originality/value - The paper is based on original case research and comparative analysis of data from different geographical contexts. It contributes to both theory and management practice about the strategic resources, decision choices, competitive environments and firm values needed to address external market demands as well as in building internal capabilities.

"Minimálbér-paradoxon" versenyzői munkaerőpiacon? ("Minimum-wage paradox" in a competitive labour market? Lessons from an experimental line of thought)

A versenyzői munkaerőpiac hagyományos kereslet-kínálati modellje az egyensúlyi bérszintet meghaladó minimálbér következményeként az egyensúlyi bérszint mellettinél alacsonyabb foglalkoztatást jósol; minél magasabb a minimálbér, annál alacsonyabbat. Empirikus vizsgálatok szerint ugyanakkor a minimálbér-emelés nem feltétlenül csökkenti a foglalkoztatást - ezt nevezik minimálbér-paradoxonnak -, ami legkézenfekvőbben a munkáltatók munkaerő-piaci monopszonerejével látszik magyarázhatónak. Ezzel szemben az a gondolatkísérlet, amelyről ez a cikk beszámol, általánosabb érvényű, versenyzői munkaerőpiacot feltételező magyarázat kidolgozására irányul. / === / In the conventional textbook demand/supply model of competitive labour markets, the introduction of a minimum wage above market-clearing level must reduce employment. Empirical findings suggest, however, that this may not always be the case, a finding most readily explained by monopsonistic competition in the labour market. The experimental line of thought reported here explores an alternative root, interpreting the "minimum-wage paradox" as the outcome of a competitive labour market that displays friction.

Shareholder ratification of the auditor and audit market competition

In my dissertation, I examine factors associated with firms’ submission of auditor selection for shareholder ratification and test if shareholder ratification of auditor selection is associated with the extent of price competition in the audit market (as measured by audit fees) and audit quality (as measured by clients’ earnings management). The dissertation is motivated from the recent recommendation of the U.S. Treasury’s Advisory Committee on Auditing Profession (ACAP) regarding the submission of auditor selection for shareholder ratification votes. The ACAP suggests that this practice may improve the competition in the audit market; yet, there is no empirical evidence supporting the ACAP’s recommendation. My dissertation attempts to fill the gap in the literature on an issue of current interest to the auditing profession. I find that firm size, CEO-Chair duality, insider ownership and institutional ownership are associated with the submission of auditor selection for shareholder ratification vote. However, I do not find an association between audit committee variables and the submission of auditor selection for shareholder ratification vote. The second essay investigates the association between auditor ratification and audit fees. Audit fees are higher in firms that submit auditor selection for shareholder ratification. The finding is not consistent with the increased price competition predicted by the ACAP. The third essay of my dissertation examine whether the submission of auditor selection for shareholder ratification is associated with earnings management. I find that firms that submit auditor selection for shareholder ratification are more likely to have lower level of earnings management. Overall, the results suggest that the same factors that are associated with higher quality monitoring also may be associated with the submission of auditor selection for shareholder ratification vote. The results call into question the one-size-fits-all approach recommended by the ACAP.

Global Pricing Strategy for a Quick-Service Restaurant Chain

The purpose of this paper is to compare prices for a popular quick-service restaurant chain (i.e. McDonalds’) across countries throughout the world using the “Big Mac Index” published by “The Economist.” The index was originally developed to measure the valuation of international currencies against the U.S. dollar. The analysis in this study examines the relationship between the price of a Big Mac and other variables such as the cost of beef, price elasticity, and income. Finally, these relationships are reviewed to draw inferences concerning the use of demand, costs, and competition in setting prices.

Shareholder Ratification of The Auditor and Audit Market Competition

In my dissertation, I examine factors associated with firms’ submission of auditor selection for shareholder ratification and test if shareholder ratification of auditor selection is associated with the extent of price competition in the audit market (as measured by audit fees) and audit quality (as measured by clients’ earnings management). The dissertation is motivated from the recent recommendation of the U.S. Treasury’s Advisory Committee on Auditing Profession (ACAP) regarding the submission of auditor selection for shareholder ratification votes. The ACAP suggests that this practice may improve the competition in the audit market; yet, there is no empirical evidence supporting the ACAP’s recommendation. My dissertation attempts to fill the gap in the literature on an issue of current interest to the auditing profession. I find that firm size, CEO-Chair duality, insider ownership and institutional ownership are associated with the submission of auditor selection for shareholder ratification vote. However, I do not find an association between audit committee variables and the submission of auditor selection for shareholder ratification vote. The second essay investigates the association between auditor ratification and audit fees. Audit fees are higher in firms that submit auditor selection for shareholder ratification. The finding is not consistent with the increased price competition predicted by the ACAP. The third essay of my dissertation examine whether the submission of auditor selection for shareholder ratification is associated with earnings management. I find that firms that submit auditor selection for shareholder ratification are more likely to have lower level of earnings management. Overall, the results suggest that the same factors that are associated with higher quality monitoring also may be associated with the submission of auditor selection for shareholder ratification vote. The results call into question the one-size-fits-all approach recommended by the ACAP.

Efficient Prices at Any Cost: Does Algorithmic Trading Deter Information Acquisition?

I demonstrate a powerful tension between acquiring information and incorporating it into asset prices, the two core elements of price discovery. As a salient case, I focus on the transformative rise of algorithmic trading (AT) typically associated with improved price efficiency. Using a measure of the relative information content of prices and a comprehensive panel of 37,325 stock-quarters of SEC market data, I establish instead that algorithmic trading strongly decreases the net amount of information in prices. The increase in price distortions associated with the AT “information gap” is roughly $42.6 billion/year for U.S. common stocks around earnings announcement events alone. Information losses are concentrated among stocks with high shares of algorithmic liquidity takers relative to algorithmic liquidity makers, suggesting that aggressive AT powerfully deters fundamental information acquisition despite its importance for translating available information into prices.

Líneas posibles de avance del modelo de Sraffa

Diversas consideraciones históricas e ideológicas han impedido la difusión de la obra fundamental de Sraffa Producción de mercancías por medio de mercancías. La obra de Sraffa ha sido estudiada fundamentalmente en sus aspectos matemáticos por economistas tales como Garegnani, Abraham-Frois, Pasinetti, Steedman, Kurz, Roncaglia, etc. pero sin desarrollar apenas sus aspectos teóricos y económicos. En este artículo se hacen algunas consideraciones sobre posibles desarrollos del libro de Sraffa a partir de su propio esquema de pensamiento.

Cloud-Architektur für Privacy-Management in kollaborativen Logistikprozessen

Durch den großen Erfolg des Cloud Computing und der hohen Geschwindigkeit, mit der Cloud-Innovationen seither Einzug in die Praxis finden, eröffnen sich für die Industrie neue Chancen im Wettbewerb. Von besonderer Bedeutung sind die Möglichkeiten, Cloud-gestützte Geschäftsprozesse dynamisch, als direkte Reaktion auf einen Kundenauftrag, anzupassen und auszuführen. Dies gilt insbesondere auch für kooperative und unternehmensübergreifende Anwendungen, welche aus mehreren IT-Diensten verschiedener Partner bestehen. Gegenstand dieses Artikels ist die Vorstellung eines Konzeptes und einer Architektur für eine zentrale Cloud-Plattform zur Konfiguration, Ausführung und Überwachung von kollaborativen Logistik-Prozessen. Auf dieser Plattform können Geschäftsprozesse modelliert und in ihren Privacy-Eigenschaften parametrisiert werden. Die einzelnen Prozesselemente werden dabei mit IT-Diensten verknüpft, die beispielsweise auf externen Cloud-Plattformen ausgeführt werden. Ein Schwerpunkt der Veröffentlichung liegt in der Betrachtung der Erstellung, Umsetzung und Überwachung von Privacy-Anforderungen.

Manipulation in U.S. REIT Investment Performance Evaluation: Empirical Evidence

We investigate whether Real Estate Investment Trust (REIT) managers actively manipulate performance measures in spite of the strict regulation under the REIT regime. We provide empirical evidence that is consistent with this hypothesis. Specifically, manipulation strategies may rely on the opportunistic use of leverage. However, manipulation does not appear to be uniform across REIT sectors and seems to become more common as the level of competition in the underlying property sector increases. We employ a set of commonly used traditional performance measures and a recently developed manipulation-proof measure (MPPM, Goetzmann, Ingersoll, Spiegel, and Welch (2007)) to evaluate the performance of 147 REITs from seven different property sectors over the period 1991-2009. Our findings suggest that the existing REIT regulation may fail to mitigate a substantial agency conflict and that investors can benefit from evaluating return information carefully in order to avoid potentially manipulative funds.

Standard Essential Patent in Telecommunication Standard: United States and China Comparison

Thesis (Ph.D.)--University of Washington, 2016-08

Trophic niche overlap of sprat and commercial small pelagic teleosts in the Gulf of Lions (NW Mediterranean Sea)

Increasing abundance of non-commercial sprats and decreasing biomass and landings of commercial anchovies and sardines justify the need to study the feeding ecology and trophic niche overlap of these planktivorous species in the Gulf of Lions. Their diet has been investigated on the basis of stomach content and stable isotope analyses in 2011 and 2012 according to different depths and regions in the study area. The main prey were Corycaeidae copepods, Clauso/Paracalanus, Euterpina acutifrons and Microsetella, for sprats and small copepods, such as Microsetella, Oncaea and Corycaeidae, for anchovies and sardines. This is the first time that the diet of sprats is described in the Gulf of Lions. Sprats fed on a larger size spectrum of prey and seem to be more generalist feeders compared to anchovies and sardines. Ontogenetic changes as well as spatial and temporal variations of the diet occurred in the three species. Stable isotope analysis revealed mobility of sardines and sprats among feeding areas while anchovies exhibited preferred feeding areas. Sprats showed a higher relative condition assessed by C/N ratios than sardines and anchovies. Our results showed an overlap of the trophic niches for the three species, indicating a potential trophic competition in the Gulf of Lions.

Essays on Information Frictions, Prices and Unemployment

I investigate the effects of information frictions in price setting decisions. I show that firms' output prices and wages are less sensitive to aggregate economic conditions when firms and workers cannot perfectly understand (or know) the aggregate state of the economy. Prices and wages respond with a lag to aggregate innovations because agents learn slowly about those changes, and this delayed adjustment in prices makes output and unemployment more sensitive to aggregate shocks. In the first chapter of this dissertation, I show that workers' noisy information about the state of the economy help us to explain why real wages are sluggish. In the context of a search and matching model, wages do not immediately respond to a positive aggregate shock because workers do not (yet) have enough information to demand higher wages. This increases firms' incentives to post more vacancies, and it makes unemployment volatile and sensitive to aggregate shocks. This mechanism is robust to two major criticisms of existing theories of sluggish wages and volatile unemployment: the flexibility of wages for new hires and the cyclicality of the opportunity cost of employment. Calibrated to U.S. data, the model explains 60% of the overall unemployment volatility. Consistent with empirical evidence, the response of unemployment to TFP shocks predicted by my model is large, hump-shaped, and peaks one year after the TFP shock, while the response of the aggregate wage is weak and delayed, peaking after two years. In the second chapter of this dissertation, I study the role of information frictions and inventories in firms' price setting decisions in the context of a monetary model. In this model, intermediate goods firms accumulate output inventories, observe aggregate variables with one period lag, and observe their nominal input prices and demand at all times. Firms face idiosyncratic shocks and cannot perfectly infer the state of nature. After a contractionary nominal shock, nominal input prices go down, and firms accumulate inventories because they perceive some positive probability that the nominal price decline is due to a good productivity shock. This prevents firms' prices from decreasing and makes current profits, households' income, and aggregate demand go down. According to my model simulations, a 1% decrease in the money growth rate causes output to decline 0.17% in the first quarter and 0.38% in the second followed by a slow recovery to the steady state. Contractionary nominal shocks also have significant effects on total investment, which remains 1% below the steady state for the first 6 quarters.