Essays on firm heterogeneity and international trade

This thesis provides four contributions to the literature on the productivity- internationalization nexus by considering some recent developments in the literature. A well-established stylized fact is reported by this literature, which is that exporters are more productive and larger than non-exporters, and two hypotheses attempt to explain this finding. The first, often referred to as the self-selection hypothesis, suggests that more productive firms select themselves into export markets, while the learning-by-exporting hypothesis highlights the role of learning from exporting. In this thesis, first, the self-selection hypothesis is revisited, and it is shown that evidence against self-selection exists in some UK industries. Second, it is demon- strated that some UK firms experience rising marginal costs, although both tra- ditional and new trade theories assume constant marginal cost. It is then shown that the evidence against self-selection that we report can be best explained by the existence of increasing, rather than constant, marginal costs. Third, the learning by exporting hypothesis is tested empirically for UK firms. Highlighting the importance of the scale effect in total factor productivity growth, it is shown that any learning by exporting effects are predominantly attributable to a change in scale efficiency. Unlike Melitz (2003), some recent studies consider some other strategies to access foreign markets, such as foreign direct investment, and cross-border mergers. Finally, following this new branch of the literature, the productivity-internationalization nexus is examined by utilizing a two-country oligopolistic model. It is shown that more productive firm might prefer greenfield investment over cross-border merger, which contradicts the findings provided by the relevant literature

Development of algorithms and software for forecasting, nowcasting and variability of TEC

Total Electron Content (TEC) is an important characteristic of the ionosphere relevant to communications. Unpredictable variability of the ionospheric parameters due to various disturbances limits the efficiencies of communications, radar and navigation systems. Therefore forecasting and nowcasting of TEC are important in the planning and operation of Earth-space and satellite-to-satellite communication systems. Near-Earth space processes are complex being highly nonlinear and time varying with random variations in parameters where mathematical modeling is extremely difficult if not impossible. Therefore data driven models such as Neural Network (NN) based models are considered and found promising in modeling such processes. In this paper the NN based METU-NN model is introduced to forecast TEC values for the intervals ranging from 1 to 24 h in advance. Forecast and nowcast of TEC values are also considered based on TEC database. Day-to-day and hour to-hour variability of TEC are also estimated using statistical methods. Another statistical approach based on the clustering technique is developed and a preprocessing approach is demonstrated for the forecast of ionospheric critical frequency foF2

Middle Ordovician acritarchs and problematic organic-walled microfossils from the Saq-Hanadir transitional beds in the QSIM-801 well, Saudi Arabia

Core samples from the QSIM-801 water well, drilled in central Saudi Arabia, cover a 93-foot interval spanning the transition between the Sajir Member of the Saq Formation, that consists mainly of sandstones of tidal sand flat environments, and the Hanadir Member of the Qasim Formation, characterized by argillaceous graptolitic mudstones, corresponding to a tidal delta front. The samples contain abundant, exceptionally well-preserved and diverse palynomorphs, which include cryptospores, acritarchs and chitinozoans, other problematic organic-walled microfossils as well as other organic particles such as cuticle-like fragments. The studied interval is biostratigraphically well constrained by the presence of chitinozoans of the formosa and pissotensis Zones of late-early to late Darriwilian age (Middle Ordovician) in the uppermost Saq Formation and Hanadir Member. The biostratigraphic age of the Sajir Member considered to span the Dapingian–Darriwilian boundary, is re-discussed based on the results herein. The uppermost part of the Sajir Member yielded the ichnofossil, Phycodes fusiforme. Acritarch assemblages from the Sajir Member of the Saq Formation are poorly diversified and dominated by sphaeromorphs. More diverse assemblages of acritarchs, associated with enigmatic forms, occur in the Hanadir Member of the Qasim Formation. The contact between the two formations and the transition between the palynomorph assemblages are sharp, suggesting a stratigraphic hiatus. A quantitative analysis allows us to discuss the paleoenvironmental changes and possibly climatic changes associated with an hypothesis of ice house conditions during this period. Among the diagnostic acritarch taxa observed are Frankea breviuscula, F. longiuscula, Baltisphaeridium ternatum, Dasydorus cirritus, Dicrodiacrodium ancoriforme, Poikilofusa ciliaris, Pterospermopsis colbathii and Uncinisphaera fusticula. These are associated with other typical forms known to range across the Lower–Middle Ordovician boundary, such as Aremoricanium rigaudae, Aureotesta clathrata, Barakella fortunata, B. rara, Baltisphaeridium klabavense, Glaucotesta latiramosa and Striatotheca spp. Galeate and peteinoid acritarchs are also well represented, as well as tiny forms of ultraplanctonic size. Three new species of acritarchs are proposed: Frankea longiuscula var. darriwilense var. nov, Micrhystridium regulum sp. nov, and Tyrannus proteus sp. nov. Repeated occurrences throughout the section of cryptospores, problematic microfossils such as organic filaments, cuticle-like tissues, striated and pigmented leiospheres frequently in clusters, are interpreted to reflect recurrent terrestrial and freshwater inputs in the depositional environment. Single-specimen, high-resolution analyses using Confocal Laser Scanning Microscopy on the enigmatic form Tyrannus proteus sp. nov. show fluorescence emission spectra and microstructural properties significantly different from those of typical marine acritarchs from the same levels

Essays on vertical market structure

Essays on vertical market structur

Alexander Bogdanov and the Question of Unity: An Emerging Research Agenda

In this paper, we propose a research agenda to support the recovery of Alexander Bogdanov’s philosophical and systemic thinking that culminated in his magnum opus, Tektology. Our main reason for doing so is to re-address enduring questions about the unity of science and the unity of the systems paradigm. Since the turn of the new millennium, there has been renewed interest in the ideal of the unity of science. General system theory (GST), cybernetics and complexity science are three significant intellectual sources inspiring this renewal. It is not unusual for these ideas to be grouped under the umbrella terms systems science or systems thinking, which are two ways to present a single systems paradigm, and we will explain why its ‘unity’ is both necessary and problematic. Bringing Bogdanov’s work back to address the unity question can help us to progress towards unity in diversity

Firm‐productivity and cross border merger

We examine whether higher productivity of a foreign firm increases the incentive for a cross border merger, which is a dominant form of foreign direct investment in recent decades. In line with the empirical evidence, we show that the relationship between productivity of a foreign firm and cross border merger is mixed. We show that the market concentration effect plays an important role in determining the relationship and provide a rationale for a generally ignored empirical evidence showing a negative relationship between firm-productivity and cross border merger. Our results hold under both Cournot and Bertrand competition

Complementary inputs, outsourcing and vertical integration: price versus quantity competition

We compare the effects of price and quantity competition in an industry with complementary inputs, outsourcing and a vertically integrated firm where vertical integration occurs between a final goods producer and a subset of input suppliers. The profit of the integrated firm and the industry profit are higher under Bertrand competition, the profit of the non-integrated firm is higher under Bertrand competition for high product differentiation, and consumer surplus and welfare are higher under Bertrand competition for low product differentiation. Further, no market foreclosure can be the preferred choice of the vertically integrated firm for any degree of product differentiation

The neural network technique - 1: a general exposition

Near earth space processes are highly complex and nonlinear and mathematical modeling based on first physical principals is usually difficult or impossible. For such cases data driven modeling methods are recommended to be used in parallel with mathematical modeling approach. Highly non-linear processes in the near-earth space are advantageously dealt with using data-driven modeling techniques in the neural network (NN) approach. The only basic requirement for its application is the availability of representative data. (C) 2003 COSPAR. Published by Elsevier Ltd. All rights reserved