The reform of mechanisms for foreign exchange allocation : theory and lessons from sub-Saharan Africa

Administrative exchange allocation has been common in developing countries, especially in sub-Saharan Africa. Steps to dismantle or modify these control mechanisms have been carried out through traditional schemes. The authors draw lessons from sub-Saharan Africa's historical experience useful both to African former socialist economies. Exchange regime reform should be given highest priority for its role in reducing anti-export bias. Although many sub-Saharan countries have attempted to reform their allocation mechanisms, only a few have made the transition to market allocation (virtually convertible currency, at least on the current account.) Failure to do so is the major shortcoming of most adjustment packages. Both gradual and rapid approaches have succeeded. On purely economic grounds (given the problems of such intermediate steps as auctions), speed is preferable but it is not always politically or institutionally feasible. The transition must be accompanied by a coherent set of fiscal and monetary policies and a willingness to allow the exchange rate to seek a true market-clearing level. Some lessons regarding the specific mechanisms, discussed in approximate order of their proximity to convertibility, are as follows. The most rudimentary transition mechanism is the own-funds scheme, which is no more than a beginning of reform. Own-funds schemes should be accompanied by liberalization of the rules governing exports, or illegal exports and the black market premium may increase. Export retention schemes can minimize the adverse effects on exporters of foreign exchange shortages, reduce the implicit export tax, and fund a legal private exchange market. But the retained funds must be saleable, the retention rates substantial, and traditional exports must be included to adequately fund the legal private exchange market. Open general licensing (OGL) and similar schemes can be a useful intermediate step in liberalizing import and exchange allocation regimes. But in practice the benefits are limited by two features. First, consumer goods competing with local production, whose imports were restricted the most, have usually been excluded, at least initially. Moreover, OGL has no endogenous price-setting mechanism for the exchange rate. The OGL rate should generally be connected to, but lower than, the parallel rate. An auction incorporates a pricing mechanism, which is an important advantage. But the pricing mechanism must be allowed to work, which has not always been the case. Auction rules should be clear (should not allow discretionary disqualification of bids, for example), should minimize participation costs, and allow wide participation. Marginal, rather than the more common Dutch, pricing system is preferred. The use of a reservation price may reduce volatility but may also impede the full disbursement of funds. The shortcomings of transitional schemes to dismantle or modify foreign exchange controls become more important the longer they are in place. A strong case can be made for avoiding delay in moving to full currency convertibility.Environmental Economics&Policies,Economic Theory&Research,Economic Stabilization,Access to Markets,Markets and Market Access

Parallel 3-D marine controlled-source electromagnetic modelling using high-order tetrahedral Nédélec elements

We present a parallel and high-order Nédélec finite element solution for the marine controlled-source electromagnetic (CSEM) forward problem in 3-D media with isotropic conductivity. Our parallel Python code is implemented on unstructured tetrahedral meshes, which support multiple-scale structures and bathymetry for general marine 3-D CSEM modelling applications. Based on a primary/secondary field approach, we solve the diffusive form of Maxwell’s equations in the low-frequency domain. We investigate the accuracy and performance advantages of our new high-order algorithm against a low-order implementation proposed in our previous work. The numerical precision of our high-order method has been successfully verified by comparisons against previously published results that are relevant in terms of scale and geological properties. A convergence study confirms that high-order polynomials offer a better trade-off between accuracy and computation time. However, the optimum choice of the polynomial order depends on both the input model and the required accuracy as revealed by our tests. Also, we extend our adaptive-meshing strategy to high-order tetrahedral elements. Using adapted meshes to both physical parameters and high-order schemes, we are able to achieve a significant reduction in computational cost without sacrificing accuracy in the modelling. Furthermore, we demonstrate the excellent performance and quasi-linear scaling of our implementation in a state-of-the-art high-performance computing architecture.This project has received funding from the European Union's Horizon 2020 programme under the Marie Sklodowska-Curie grant agreement No. 777778. Furthermore, the research leading to these results has received funding from the European Union's Horizon 2020 programme under the ChEESE Project (https://cheese-coe.eu/ ), grant agreement No. 823844. In addition, the authors would also like to thank the support of the Ministerio de Educación y Ciencia (Spain) under Projects TEC2016-80386-P and TIN2016-80957-P. The authors would like to thank the Editors-in-Chief and to both reviewers, Dr. Martin Cuma and Dr. Raphael Rochlitz, for their valuable comments and suggestions which helped to improve the quality of the manuscript. This work benefited from the valuable suggestions, comments, and proofreading of Dr. Otilio Rojas (BSC). Last but not least, Octavio Castillo-Reyes thanks Natalia Gutierrez (BSC) for her support in CSEM modeling with BSIT.Peer ReviewedPostprint (author's final draft

Improving edge finite element assembly for geophysical electromagnetic modelling on shared-memory architectures

This work presents a set of node-level optimizations to perform the assembly of edge finite element matrices that arise in 3D geophysical electromagnetic modelling on shared-memory architectures. Firstly, we describe the traditional and sequential assembly approach. Secondly, we depict our vectorized and shared-memory strategy which does not require any low level instructions because it is based on an interpreted programming language, namely, Python. As a result, we obtained a simple parallel-vectorized algorithm whose runtime performance is considerably better than sequential version. The set of optimizations have been included to the work-flow of the Parallel Edge-based Tool for Geophysical Electromagnetic Modelling (PETGEM) which is developed as open-source at the Barcelona Supercomputing Center. Finally, we present numerical results for a set of tests in order to illustrate the performance of our strategy.This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 644202. The research leading to these results has received funding from the European Union's Horizon 2020 Programme (2014-2020) and from Brazilian Ministry of Science, Technology and Innovation through Rede Nacional de Pesquisa (RNP) under the HPC4E Project (www.hpc4e.eu), grant agreement No. 689772. Authors gratefully acknowledge the support from the Mexican National Council for Science and Technology (CONACYT). All numerical tests were performed on the MareNostrum supercomputer of the Barcelona Supercomputing Center - Centro Nacional de Supercomputación (www.bsc.es).Peer ReviewedPostprint (author's final draft

RNAseq analysis of fast skeletal muscle in restriction-fed transgenic coho salmon (Oncorhynchus kisutch) : an experimental model uncoupling the growth hormone and nutritional signals regulating growth

Background Coho salmon (Oncorhynchus kisutch) transgenic for growth hormone (Gh) express Gh in multiple tissues which results in increased appetite and continuous high growth with satiation feeding. Restricting Gh-transgenics to the same lower ration (TR) as wild-type fish (WT) results in similar growth, but with the recruitment of fewer, larger diameter, muscle skeletal fibres to reach a given body size. In order to better understand the genetic mechanisms behind these different patterns of muscle growth and to investigate how the decoupling of Gh and nutritional signals affects gene regulation we used RNA-seq to compare the fast skeletal muscle transcriptome in TR and WT coho salmon. Results Illumina sequencing of individually barcoded libraries from 6 WT and 6 TR coho salmon yielded 704,550,985 paired end reads which were used to construct 323,115 contigs containing 19,093 unique genes of which >10,000 contained >90 % of the coding sequence. Transcripts coding for 31 genes required for myoblast fusion were identified with 22 significantly downregulated in TR relative to WT fish, including 10 (vaspa, cdh15, graf1, crk, crkl, dock1, trio, plekho1a, cdc42a and dock5) associated with signaling through the cell surface protein cadherin. Nineteen out of 44 (43 %) translation initiation factors and 14 of 47 (30 %) protein chaperones were upregulated in TR relative to WT fish. Conclusions TR coho salmon showed increased growth hormone transcripts and gene expression associated with protein synthesis and folding than WT fish even though net rates of protein accretion were similar. The uncoupling of Gh and amino acid signals likely results in additional costs of transcription associated with protein turnover in TR fish. The predicted reduction in the ionic costs of homeostasis in TR fish associated with increased fibre size were shown to involve multiple pathways regulating myotube fusion, particularly cadherin signaling.Publisher PDFPeer reviewe

Interactions between marine picoeukaryotes and their viruses one cell at a time = Interacciones entre picoeucariotas marinos y sus virus célula a célula

[eng] Marine viruses are key components of marine microbial communities, as they influence the cellular abundances and the community structure of microbes, participate in their genetic exchange, and intervene in the ocean biogeochemical cycles. Most studies dealing with the role of viruses in the marine environment have been done from a bulk community point of view, but going from the bulk community perspective to specific virus─host relationships is essential in order to understand the role of viruses in shaping a determined host community, in modifying host genomes, and ultimately in the release of organic compounds from the lysed cells. For this reason, in this thesis we implemented and applied different methodologies that are able to detect, visualize and quantify virus─host interactions in marine eukaryotes at the single cell level. We focused on picoeukaryotes (cells <3 µm) because they play crucial roles in marine food webs and biogeochemical cycles, and virus─host interactions in natural populations of these minute eukaryotes are largely unknown. In the first chapter we combined previously developed techniques, used to assess prokaryotic host─phage interactions, to implement VirusFISH for detecting specific virus─host dynamics, using as a model system the photosynthetic picoeukaryote Ostreoccocus tauri and its virus OtV5. With the VirusFISH technique, we could also monitor the infection, as well as quantify the free viruses produced during the lysis of the host in a non-axenic culture, which allowed the calculation of the burst size. This study set the ground for the application of the VirusFISH technique to natural samples. In the second chapter of this thesis, we applied VirusFISH to seawater samples from the Bay of Biscay (Cantabrian Sea) to study the dynamics of viral infection in natural populations of Ostreococcus along a seasonal cycle. We were able to quantify the percentage of cells infected over time, and compared these results with the transcriptional viral and host activities derived from metatranscriptomic data. This constitutes the first study where a specific viral─host interaction has been visualized and monitored over time in a natural system. Picoeukaryotes in the ocean are prevalently uncultured, and thus, in the third chapter of this thesis we went an step further to unveil novel viral─host relationships in eukaryotic uncultured hosts. For this purpose, we mined single amplified genomes (SAGs) of picoeukaryotes obtained during the Tara Oceans expedition for viral signatures. We found that almost 60% of the cells analyzed presented an associated virus with narrow host specificity. Some of the viral sequences were widely distributed and some geographically constrained, and they were preferentially found at the deep chlorophyll maximum. Moreover, we found a mavirus virophage potentially integrated in four SAGs of two different lineages, suggesting the presence of virophages is more common than previously thought. In summary, in this thesis we have implemented and used techniques that allow us to detect and monitor specific virus─host interactions, which is one of the major challenges in marine viral ecology. On the one hand, VirusFISH arises as a powerful technique that can be easily adapted to any host─virus system that has been genome-sequenced. On the other hand, the results obtained with the single cell genomics offer the opportunity to formulate hypothesis based on detected viral─host interactions in uncultured prevalent marine picoeukaryotes, which can be later tested using experimental approaches.[spa] Se han realizado muchos estudios sobre el rol de los virus en ambientes marinos desde el punto de vista de comunidad global, pero es esencial que vayamos hacía una visión más específica de relación virus─hospedador. Por ello, en esta tesis implementamos y aplicamos diferentes metodologías para estudiar interacciones virus─hospedador, centrándonos en picoeucariotas marinos ya que se conoce muy poco de ellos en poblaciones naturales. En el primer capítulo implementamos la técnica VirusFISH, permitiendo detectar dinámicas específicas virus─hospedador eucarióticos, usando como modelo Ostreococcus tauri y su virus OtV5. VirusFISH permitió monitorizar la infección, cuantificar en un cultivo no axénico los virus libres producidos durante la lisis y calcular el tamaño de explosión. Este estudio estableció la base para la aplicación de VirusFISH en muestras naturales. En el segundo capítulo aplicamos VirusFISH en muestras de agua natural para estudiar las dinámicas de infección en Ostreococcus. Cuantificamos el porcentaje de células infectadas durante un ciclo estacional y lo comparamos con las actividades transcripcionales de virus y Ostreococcus spp. Este constituye el primer estudio donde se visualiza y monitoriza una interacción específica virus─hospedador en el tiempo en un sistema natural. En el tercer capítulo descubrimos nuevas relaciones virus─hospedador en células no cultivadas, analizando genomas amplificados individuales de picoeucariotas, encontrando que la mayoría de las células presentaron al menos un virus. Estas secuencias víricas se encontraron preferentemente en el máximo profundo de clorofila, algunas de ellas ampliamente distribuidas por los océanos y otras constreñidas geográficamente. Además, encontramos un virofago mavirus potencialmente integrado en dos linajes distintos, sugiriendo que los virofagos son más comunes de lo que se pensaba. En resumen, hemos implementado y usado técnicas que nos han permitido detectar y monitorizar interacciones específicas virus─hospedador, uno de los mayores retos en la ecología microbiana marina. Por un lado, VirusFISH surge como una técnica potente que puede ser fácilmente adaptada a cualquier sistema virus─hospedador del cual tengamos el genoma secuenciado. Por otro lado, los resultados obtenidos con la genómica de célula individual muestran la oportunidad de formular hipótesis basadas en interacciones virus─hospedador detectadas en picoeucariotas marinos no cultivados, que pueden ser posteriormente testadas mediante aproximaciones experimentales

Lengua, derecho y medios de comunicación

La lengua como realidad cultural y social puede ser enfocada desde múltiples perspectivas. Para los juristas, la más fundamental y habitual es la que señala el uso de la lengua como un derecho vinculado al libre desenvolvimiento de la personalidad, manifestación de la dignidad de la persona humana y de los derechos que le son inherentes, y conecta el uso de la lengua, inmediatamente, con el artículo 20 de la Constitución, que reconoce el derecho a la libertad de expresión y de información