1,721,047 research outputs found
Backward and Forward Integration Along Global Value Chains
No full textBoth backward (upstream) and forward (downstream) vertical integration strategies shape the organization of global value chains (GVCs). Yet, many studies make the unrealistic assumption that integration decisions are binary and one-directional. That is, for each production stage, companies make the integration decision only once, and this can be either backward or forward but not in both directions. The aim of this paper is to analyze the firm-level organization of GVCs when both vertical integration decisions are taken into account. Exploiting a global sample of more than 1.4 million firms, we first document how midstream parents, which actually integrate on both directions along the chain, are at least as common as downstream and upstream parents. We then find that parent companies prefer to integrate production stages with a relatively low elasticity of substitution and with a technological proximity on the supply chain. Finally, we provide evidence that more than one subsidiary in a given location can perform the same production stage
Global value chains: New evidence for North Africa
No full textThis paper analyzes the participation and the position of North African countries in global value chains (GVCs). Exploiting the recently released Eora multiregional Input-Output tables, we describe regional and country GVC involvement. North African countries have not so far been able to fully integrate into international production networks. However, a large part of their (low) trade is due to value added related activities, mainly in the upstream phases, and the importance of foreign linkages has been increasing over time. We complement the Input-Output analysis with sectoral evidence from selected case studies and policy experiences. Overall, our results suggest that enhancing the GVC participation of North African countries has potential to substantially benefit local industries, countries and indeed the whole area. However, the ability to retain such benefits relies on specific local conditions, such as a favorable environment for foreign investments, and lower trade barriers, thus leaving room for policy intervention
Global value chains participation and productivity gains for North African firms
No full textThe emergence of global value chains (GVCs) has provided some firms the opportunity to internationalize by specializing in the production of specific inputs or tasks along the chain, with a direct impact on a country’s competitiveness. China, for instance, managed to enter low value added phases in GVCs to rapidly become a major player in world trade. Against this background, this paper asks whether North Africa, given its favourable geographic position in the Mediterranean and proximity to Europe, can grab similar opportunities. In particular, it analyzes the GVCs participation of North African firms and its implications for productivity. Since the coordination of vertically fragmented production processes increasingly relies on an adequate level of quality and reliability, especially when the inputs from several stages and locations must come together in a specific way, we identify firms involved in GVCs as traders with internationally recognized quality certification. Using a propensity score matching diff-in-diff method, the paper finds that firms that enter GVCs both perform better ex ante and show additional productivity gains ex post. Results suggest that policies designed to support certifications and compliance with international standards and to increase trust between firms in different countries, represent an important tool for linking developing countries to global production networks, with possible positive consequences on their economic development and growth
A Novel Approach to Realize Plasmonic Sensors via Multimode Optical Waveguides: A Review
No full textIn recent decades, the Surface Plasmon Resonance (SPR) phenomenon has been utilized as an underlying technique in a broad range of application fields. Herein, a new measuring strategy which harnesses the SPR technique in a way that is different from the classical methodology was explored by taking advantage of the characteristics of multimode waveguides, such as plastic optical fibers (POFs) or hetero-core fibers. The sensor systems based on this innovative sensing approach were designed, fabricated, and investigated to assess their ability to measure various physical features, such as magnetic field, temperature, force, and volume, and to realize chemical sensors. In more detail, a sensitive patch of fiber was used in series with a multimodal waveguide where the SPR took place, to alter the mode profile of the light at the input of the waveguide itself. In fact, when the changes of the physical feature of interest acted on the sensitive patch, a variation of the incident angles of the light launched in the multimodal waveguide occurred, and, as a consequence, a shift in resonance wavelength took place. The proposed approach permitted the separation of the measurand interaction zone and the SPR zone. This meant that the SPR zone could be realized only with a buffer layer and a metallic film, thus optimizing the total thickness of the layers for the best sensitivity, regardless of the measurand type. The proposed review aims to summarize the capabilities of this innovative sensing approach to realize several types of sensors for different application fields, showing the high performances obtained by exploiting a simple production process and an easy experimental setup
A New Way of Using Plasmonic Phenomena in Optical Fibers to Realize Highly Sensitive Sensors: What Prospects?
No full textA novel sensing approach has been presented. The Surface Plasmon Resonance (SPR) and the properties of multimodal plastic optical fibers (POFs) have been used to implement this novel approach. For instance, the proposed sensor systems harnessing this method have been designed, realized, and tested to detect a magnetic field, temperature, and force. More in detail, the physical quantity under test interacts with a sensitive patch (a modified multimode POF), changing the light mode profile at the input of an SPR-POF platform combined with a dielectric medium at a fixed refractive index. This method allowed to use of the SPR platform without any additive sensing layer, obtaining very interesting results compared to the traditional plasmonic sensing approach
Analysis of Plasmonic Sensors Performance Realized by Exploiting Different UV-Cured Optical Adhesives Combined with Plastic Optical Fibers
No full textPolymer-based surface plasmon resonance (SPR) sensors can be used to realize simple, small-size, disposable, and low-cost biosensors for application in several fields, e.g., healthcare. The performance of SPR sensors based on optical waveguides can be changed by tuning several parameters, such as the dimensions and the shape of the waveguides, the refractive index of the core, and the metal nanofilms used to excite the SPR phenomenon. In this work, in order to develop, experimentally test, and compare several polymer-based plasmonic sensors, realized by using waveguides with different core refractive indices, optical adhesives and 3D printed blocks with a trench inside have been used. In particular, the sensors are realized by filling the blocks’ trenches (with two plastic optical fibers located at the end of these) with different UV-cured optical adhesives and then covering them with the same bilayer to excite the SPR phenomenon. The developed SPR sensors have been characterized by numerical and experimental results. Finally, in order to propose photonic solutions for healthcare, a comparative analysis has been reported to choose the best sensor configuration useful for developing low-cost biosensors
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