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

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

“Semi-fretless Guitar Invention and Method Writing”

Semi-fretless guitar is a new invention that let musician play the tonal and makam music with only one instrument. This invention that we propose is constructed on an organology and ethno-organology of chordophones played by strumming. In fact the invention has no need to be limited by guitar because the specialty of the invention is on his fret system so it can be done in all chordophones with fretboard/fingerboard. In the other hand it is better to start to work on the invention by limitation of instrument and model for optimization of capacity of being achieved. It would be good to clarify the essential instruments who gave the inspiration for the production of semi-fretless guitar; the guitar from the western culture with tonal music and the oud from the eastern culture with makam music. It is very important to prepare a multiculturally rich method of this guitar firstly in English with tonal and makam references.</jats:p

Essays on vertical market structure

Essays on vertical market structur

Essays on vertical market structure

Essays on vertical market structur