14,704 research outputs found

    Cu,Zn,Al layered double hydroxides as precursors for copper catalysts in methanol steam reforming – pH-controlled synthesis by microemulsion technique

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    By co-precipitation inside microemulsion droplets a Cu-based catalyst precursor was prepared with a Cu:Zn:Al ratio of 50:17:33. A pH-controlled synthesis was applied by simultaneous dosing of metal solution and precipitation agent. This technique allows for continuous operation of the synthesis and enables easy and feasible up-scaling. For comparison conventional co-precipitation was applied with the same composition. Both techniques resulted in phase pure layered double hydroxide precursors and finally (after calcination and reduction) in small Cu nanoparticles (8 nm) and ZnAl2O4. By applying the microemulsion technique smaller Cu/ZnAl2O4 aggregates with less embedded Cu particles were obtained. The microemulsion product exhibited a higher BET and specific Cu surface area and also a higher absolute catalytic activity in methanol steam reforming. However, the Cu surface area-normalized, intrinsic activity was lower. This observation was related to differences in interactions of Cu metal and oxide phase

    Tax competition, location, and horizontal foreign direct investment

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    We develop a model of capital tax/subsidy competition in which imperfectly competitive firms choose both the number and the location of the plants they operate. The endogenous presence of horizontal multinationals is shown to attenuate the “race to the bottom” and yields some results that are opposite to traditional findings in the tax competition literature. First, in the presence of horizontal multinationals, increasing subsidies decrease firms' profits by exacerbating price competition due to more firms ‘going multinational’. Second, instead of being always subsidized, capital may actually be taxed in equilibrium. Third, taxes/subsidies become strategically independent policy instruments, instead of being strategic complements. Last, there may exist multiple equilibria with either low or high subsidies.capital tax competition; international trade; horizontal multinationals; foreign direct investment; imperfect competition

    Transportation, freight rates, and economic geography

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    We investigate the role of the transport sector in structuring the location of economic activity within two-region economic geography models of the footloose capital and core-periphery types. In our setting, competitive carriers offer transport services for shipping manufactured goods across regions and freight rates are determined endogenously to clear transport markets. Each carrier commits to the maximum capacity for a round-trip and thus faces a simple logistic problem: there are costs associated with 'returning empty', and those costs increase the freight rates charged to manufacturing firms. Since demand for transport services depends on the spatial distribution of economic activity, agglomeration in one region raises freight rates to serve foreign markets, thus generating an additional dispersion force. We show that a more equal equilibrium distribution of firms prevails when freight rates are endogenously determined than when they are exogenous and that multiple equilibria (including partial agglomeration) usually coexist.transport sector, freight rates, economic geography, trade.

    Solid-state combustion synthesis of ceramics and alloys in reduced gravity

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    Possible microgravity effects are explored in the combustion synthesis of ceramics and alloys from their constituent elements. Molten intermediates are typically present during the combustion process, thereby offering the chance for natural convection to take place. Numerical simulations suggest that the combustion front in concert with gravity may act as a partial zone-refinement mechanism which is attempting to sweep out porosity in the sample. Contrary to suggestions by dimensional analysis, no effects on the combustion rate are seen. An analytical model of the combustion velocity as a function of the gravitational field and the spreading rate of molten material gives the correct order of magnitude of the gravity effect as measured by centrifuge experiments

    Transfer Pricing Rules, OECD Guidelines, and Market Distortions

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    We study the impact of transfer pricing rules on sales prices, firms’ organizational structure, and consumers’ utility within a two-country monopolistic competition model featuring source-based profit taxes that differ across countries. Firms can either become multinationals, i.e., they serve the foreign market through a fully controlled affiliate; or they can become exporters, i.e., they serve the foreign market by contracting with an independent distributor. Compared to the benchmark cases, where tax authorities are either unable to audit firms or where they are able to audit them perfectly, the use of the OECD’s Comparable Uncontrolled Price (CUP) or Cost-Plus (CP) rule distorts firms’ output and pricing decisions. The reason is that the comparable arm’s length transactions between exporters and distributors, which serve as benchmarks, are not efficient. We show that implementing the CUP or CP rules is detrimental to consumers in the low tax country, yet benefits consumers in the high tax country.Transfer pricing, OECD guidelines, multinationals and exporters, organizational choice, arm's length principle

    NK cells as effectors of acquired immune responses: effector CD4+ T cell-dependent activation of NK cells following vaccination.

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    We characterized vaccine-induced cellular responses to rabies virus in naive adult volunteers. Contrary to current paradigms, we observed potent and prolonged in vitro NK cell cytokine production and degranulation responses after restimulation of PBMCs with inactivated rabies virus in vaccinated, but not in unvaccinated, individuals. This "recall" NK cell response was absolutely dependent on Ag-specific IL-2 from CD45RO(+) CD4(+) T cells as well as IL-12 and IL-18 from accessory cells. Importantly, NK cells represented over 70% of all IFN-gamma-secreting and degranulating cells in the first 12-18 h after virus rechallenge indicating they may be required for rapid control of infection after vaccination. Activation of NK cells may be a critical function of IL-2-secreting effector memory T cells. Although IL-2-dependent postvaccination NK cell activation has been reported previously, this is the first time the magnitude of this effect and its contribution to the overall vaccine-induced response has been appreciated and the mechanisms of NK activation postvaccination have been elucidated. Our data will allow standard protocols for evaluating vaccine-induced immunity to be adapted to assess NK cell effector responses

    Characterization of spatio-temporal epidural event-related potentials for mouse models of psychiatric disorders.

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    Distinctive features in sensory event-related potentials (ERPs) are endophenotypic biomarkers of psychiatric disorders, widely studied using electroencephalographic (EEG) methods in humans and model animals. Despite the popularity and unique significance of the mouse as a model species in basic research, existing EEG methods applicable to mice are far less powerful than those available for humans and large animals. We developed a new method for multi-channel epidural ERP characterization in behaving mice with high precision, reliability and convenience and report an application to time-domain ERP feature characterization of the Sp4 hypomorphic mouse model for schizophrenia. Compared to previous methods, our spatio-temporal ERP measurement robustly improved the resolving power of key signatures characteristic of the disease model. The high performance and low cost of this technique makes it suitable for high-throughput behavioral and pharmacological studies

    Methanol Chemistry

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    Designing SANDRA: An autonomous tour guide robot for the University of Technology, Sydney

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    This paper describes how a team of final year mechatronic engineering students developed an autonomous robotic system intended to act as a tour guide during events such as University open days and explores the opportunities this project presented to extend their knowledge and skills. The specifications of the project required the system to localise and navigate autonomously within a known environment while avoiding collisions with any people or obstacles not included in the prior area map. In addition to these requirements, the system needed to locate humans as potential clients, approach and greet them, offer directions and if required take the guest on a guided tour of the university. While taking the subject Advanced Robotics the students were able to develop a functional first prototype of the system and carry out initial tests. Following the completion of the subject a small number of the students opted to continue working on the project developing a second prototype using the knowledge gained and further enhancing their learning experiences. While this project mainly involved integrating existing well known algorithms, software and hardware, it provided an excellent opportunity to enhance the mechatronic engineering skills of the students involved
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