Estudio regional sobre la economía de los biocombustibles en 2010: temas clave para los países de América Latina y el Caribe

Incluye BibliografíaEl estudio busca dar una mirada actualizada de los tópicos relevantes en el desarrollo global de los biocombustibles, con el objeto de identificar oportunidades y riesgos clave para los países de América Latina y el Caribe. En los primeros cuatro capítulos se plantea un contexto general, en el que se define y explica brevemente qué son los biocombustibles, cuáles son las materias primas utilizadas para su producción y las principales tecnologías de conversión; se analizan las tendencias en el mercado global, tanto en la producción, comercio y costos, así como sus proyecciones a futuro; y se discuten las políticas para su promoción, tanto en los principales países productores a nivel global como en los países de ALC. En cada caso se discuten cuáles son los temas relevantes para ALC. A partir del capítulo V se analizan temas específicos, relativos a las temáticas ambiental y socioeconómica y a los vínculos con la seguridad alimentaria, identificando en cada caso temas relevantes para ALC. En materia ambiental el análisis abarca los debates sobre su contenido energético, emisiones de gases de efecto invernadero, emisiones locales, uso y contaminación de aguas, uso de tierras y contaminación de suelo, entre las más importantes. En materia socio-económica se analizan los impactos sobre la balanza de pagos, nivel y calidad de empleo, inclusión de pequeños agricultores, acceso a tierras y acceso a servicios básicos. El documento concluye con un conjunto de recomendaciones de política para los gobiernos de ALC

Design of a waveguide-coupled GeSn disk laser

We report on the design of a waveguide coupled GeSn microdisk-laser cavity in which the germanium virtual substrate serving as a template for GeSn growth is repurposed for the definition of passive on-chip interconnection waveguides. A main challenge resides in transferring the optical power from the upper (Si)GeSn gain stack to the underlying virtual substrate layer and is solved with laser mode engineering. Designs are based on experimentally realized layer stacks and waveguide outcoupling efficiencies as high as 27% are shown in compact resonator geometries with a small, 7 $\mu$m radius, with 42% of the power being recycled in the laser cavity

SiGeSn/GeSn hetero- and multiple quantum well structures for optoelectronics on Si

Advanced information technology has to be able to cope with the enormous amounts and rates of data requirements. New architectures of computing systems, such as neuromorphic computing, will enable deep learning and massive parallel data handling. However, it will need also large amounts of data for training as well as fast transfer rates of data between logic and storage devices. Here, advanced chip and board designs, including silicon optical interposer may allow much higher density of signal traces between co-packaged chips. In particular co-packaged silicon photonic chips allow optical interconnections between systems-in-package. Thus silicon interposer can directly contain photonic devices based on group alloys. In a long term vision this technology might be enabled by GeSn lasers permitting to connect optically individual chips within the system-in-package.In the past years significant progress has been made to develop optically active devices based on Si. A direct band gap for GeSn alloys containing more than 8.5% of Sn was demonstrated and the optically pumped GeSn laser were reported [1,2]. In order to improve the device performance and achieve electrical operation at sufficiently low power still severe challenges have to be met. The GeSn active region has to be embedded in a heterostructure providing optical waveguiding and efficient carrier injection. The active region may contain quantum well structures to warrant low threshold currents and room temperature operation. Please click Additional Files below to see the full abstract

Strain engineering for GeSn/SiGeSn multiple quantum well laser structures

Optically pumped GeSn laser have been realized, thus alloying of group IV elements germanium (Ge) and tin (Sn) has a large potential to be a solution for Si-photonics, since a direct bandgap for Sn incorporations above ~9 at.% is obtained [1]. The value of the bandgap can further be controlled by adding Si into the mix, which can be exploited for the formation of heterostructures for carrier confinement [2]. However, a sufficiently large difference in energy ΔE between the indirect L-valley and the direct Г-valley is required to achieve room temperature lasing. Recently lasing was reported at 180K in GeSn alloys with Sn concentrations as high as 22,3% [3]. Alternatively ΔE can be increased by adding tensile strain to the GeSn layers. Here we will discuss that an appropriate combination of Sn concentration and strain will be advantageous to tailor gain and temperature stability of the structures. Please click Additional Files below to see the full abstract

Digital games, cognitive skills, and motivation: : children’s perception in the school context

In addition to entertainment, games have been recognized as enhancers of cognition and associated with increased motivation in the school learning context. The possibility of immersion and active player participation is considered a distinguished aspects of game design. Therefore, this study proposed the application of Brain School’s digital games using tablets during a school year, with weekly interventions of 50 minutes in a class of the second year of elementary school. Twenty-five students were analyzed with an average of eight years old. At the end of the interventions, the evaluation was carried out through individual interviews. The results revealed that most of children felt motivated to participate in the games activities. However, there was no association between level of motivation and cognitive skills investigated (attention and problem solving), nor between preferred games and cognitive skills trained. However, qualitative data showed that children liked using games and acknowledged that the activity contributed with the exercise of their abilities. In general, this research contributed to reinforcing the importance of the diversification of methodological strategies which include the use of digital games in education

ARTEFACTS: How do we want to deal with the future of our one and only planet?

The European Commission’s Science and Knowledge Service, the Joint Research Centre (JRC), decided to try working hand-in-hand with leading European science centres and museums. Behind this decision was the idea that the JRC could better support EU Institutions in engaging with the European public. The fact that European Union policies are firmly based on scientific evidence is a strong message which the JRC is uniquely able to illustrate. Such a collaboration would not only provide a platform to explain the benefits of EU policies to our daily lives but also provide an opportunity for European citizens to engage by taking a more active part in the EU policy making process for the future. A PILOT PROGRAMME To test the idea, the JRC launched an experimental programme to work with science museums: a perfect partner for three compelling reasons. Firstly, they attract a large and growing number of visitors. Leading science museums in Europe have typically 500 000 visitors per year. Furthermore, they are based in large European cities and attract local visitors as well as tourists from across Europe and beyond. The second reason for working with museums is that they have mastered the art of how to communicate key elements of sophisticated arguments across to the public and making complex topics of public interest readily accessible. That is a high-value added skill and a crucial part of the valorisation of public-funded research, never to be underestimated. Finally museums are, at present, undergoing something of a renaissance. Museums today are vibrant environments offering new techniques and technologies to both inform and entertain, and attract visitors of all demographics.JRC.H.2-Knowledge Management Methodologies, Communities and Disseminatio

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Group IV (Si)GeSn light emission and lasing studies

To enable the continuous evolution of information technology, increasing data transferrates are demanded. This is accompanied by rising power consumption and requisition of larger bandwidths. The integration of photonics with electronic circuits provides a solution, which facilitates the decrease of heat dissipation and allows transmitting data in parallel with the speed of light, boosting the performance ofintegrated circuits. Such a concept is preferably realized within the highly elaborated silicon processing technology, on which the whole information technology isbased on. The most pressing issue, missing for the fully integration of photonicsto electronics, is an integrated light source. Silicon-germanium-tin (SiGeSn) alloysoffer a promising extension of this platform, since they can be monolithically grownon Si and their direct bandgap in specific configurations was proven in 2015. This thesis summarizes studies on spontaneous and stimulated emission of GeSnalloys mainly based on photoluminescence (PL) and electroluminescence (EL) spectroscopy. The effect of strain relaxation in GeSn alloys, grown on top of Ge virtual substrates, on optical properties is investigated. The temperature trend of spontaneous emission provides insight on the contribution of non-radiative defect recombination. It also illustrates the indirect-to-direct bandgap transition in Ge0.875Sn0.125alloys under strain relaxation. Heterostructure PL analysis emphasizes the importance of defect engineering, since presence of defects close to the active layer heavily deteriorates light emission. To prove the concept of electrical carrier injection, GeSn-based LEDs are fabricated. Electroluminescence spectra unveil similar temperature dependent behavior as PLfrom unprocessed layers, with comparable defect-induced limitations. The examination of Ge and SiGeSn as barrier materials in multi-quantum-wells (MQWs) provesSiGeSn as the material of choice due to a better carrier confinement. Subsequently, stimulated emission from undercut microdisk cavities is investigated. For the first time, single layer GeSn microdisk lasers are presented, offering increased mode confinement due to high refractive index contrasts compared to commonFabry-Pérot lasers. The undercut leads to an almost complete strain relaxationmodifying the band structure of the gain material. Even "just direct" GeSn alloys are proven to be suitable as gain material.To further enhance the electron population at the direct Γ-valley, which is still limitedby the moderate difference between L- and Γ-valley, in-situ n-doping of directbandgap GeSn is studied. Lasing is detected in these materials, however, showing no advantage compared to the undoped lasers. This is attributed to simultaneously increased defect recombination. The first GeSn/SiGeSn heterostructure lasers yield record low thresholds in an MQW design, enabled by carrier confinement, screening from misfit dislocations and a 2D density of states. Limitations were found, on one hand, in layer stacks with large volume-strain, hindering efficient barriers from shielding defective regions. On the other hand, directness and barrier offsets are reduced by strong quantization effects. Finally, a process flow for electrically-driven laser designs with micro ring and waveguidegeometry is introduced, underlining the applicability of group IV photonics integration into Si technology