39 research outputs found

    Quantum spin fluctuations and the stability of atomically-sized Bloch points

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    We reveal the role of the spin variables' zero-point fluctuations (ZPFs) on the stability of Bloch point (BP) singularities. As topological solitons, BPs are important in topological transitions in nanomagnets. BPs present a singularity at their core, where the long-length-scale approximation fails. We found that ZPFs bloom nearby this core, reducing the effective magnetic moment and increasing the BP's stability. As suggested by classical models, the magnonic eigenmodes found by our methods fit with the bound state of an electron surrounding a dyon, with a magnetic and an electric charge.Comment: Main: 5 pages, 4 figures. Supplementary material: 3 pages, 4 figure

    Aireación en la tecnología Biofloc (BTF): principios básicos, aplicaciones y perspectivas

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    In a globalized world with growing population avid for nutrients for their feeding, the aquatic originated protein emerges as the big nutritional alternative of the century. The reduction of their resources to the farming (water, field and human resource) implies that the fish and shrimp production has to be intensify and one of the possibilities for this development is Biofloc Technology (BFT). Nevertheless, this intensification has to be given with principles of economic and technical efficiency, therefore, a correct design of the aeration is a big principal to maintain the suspended particles, oxygenate and move the water correctly. The electricity (aeration included) join with the feed are the most important production costs using BFT. With water changes low or none of it, the number, type and distribution of the mechanical oxygenator devices are crucial to maintain the water quality for the cultivated species and for the microorganisms that are included on the system. In this context this revision pretends to present the basis for the study and implementation of the aeration systems on BFT, also drawing future perspectives for these components.En un mundo globalizado de creciente población ávido por nutrientes para su alimentación, la proteína de origen acuática emerge como la gran alternativa nutricional del siglo. La disminución de sus recursos para la explotación (agua, tierra y personal) implica que se deba intensificar la producción de peces y camarones y una posibilidad para dicho establecimiento es la tecnología de biofloc (BFT en su sigla en inglés). Sin embargo, esta intensificación debe ser dada con principios de eficiencia técnica y económica, por lo tanto, un correcto diseño de la aeración es de fundamental importancia para mantener las partículas en suspensión, oxigenar y mover correctamente el agua. Unido a los alimentos concentrados, el costo energético (incluyendo la aeración) son de los más importantes costos de producción usados en la tecnología BFT. Utilizando recambios mínimos o nulos, el número, tipo y distribución de los aparatos mecánicos de aeración son cruciales para el mantenimiento de la calidad de agua para las especies cultivadas y para los microorganismos que se encuentran inmiscuidos en el sistema. En este contexto, esta revisión pretende brindar una base teórica para el estudio e implementación de los sistemas de aireación en los sistemas BFT, además de trazar perspectivas futuras para estos componentes.En un mundo globalizado de creciente población ávido por nutrientes para su alimentación, la proteína de origen acuática emerge como la gran alternativa nutricional del siglo. La disminución de sus recursos para la explotación (agua, tierra y personal) implica que se deba intensificar la producción de peces y camarones y una posibilidad para dicho establecimiento es la tecnología de biofloc (BFT en su sigla en inglés). Sin embargo, esta intensificación debe ser dada con principios de eficiencia técnica y económica, por lo tanto, un correcto diseño de la aeración es de fundamental importancia para mantener las partículas en suspensión, oxigenar y mover correctamente el agua. Unido a los alimentos concentrados, el costo energético (incluyendo la aeración) son de los más importantes costos de producción utilizando la tecnología BFT. Utilizando recambios mínimos o nulos, el número, tipo y distribución de los aparatos mecánicos de aeración son cruciales para el mantenimiento de la calidad de agua para las especies cultivadas y para los microorganismos que se encuentran inmiscuidos en el sistema. En este contexto, esta revisión pretende brindar una base teórica para el estudio e implementación de los sistemas de aireación en los sistemas BFT, además de trazar perspectivas futuras para estos componentes.In a globalized world with growing population avid for nutrients for their feeding, the aquatic originated protein emerges as the big nutritional alternative of the century. The reduction of their resources to the farming (water, field and human resource) implies that the fish and shrimp production has to be intensify and one of the possibilities for this development is Biofloc Technology (BFT). Nevertheless, this intensification has to be given with principles of economic and technical efficiency, therefore, a correct design of the aeration is a big principal to maintain the suspended particles, oxygenate and move the water correctly. The electricity (aeration included) join with the feed are the most important production costs using BFT. With water changes low or none of it, the number, type and distribution of the mechanical oxygenator devices are crucial to maintain the water quality for the cultivated species and for the microorganisms that are included on the system. In this context this revision pretends to present the basis for the study and implementation of the aeration systems on BFT, also drawing future perspectives for these components

    ¿Por qué implementar estudios de largo plazo en el bosque seco tropical del Caribe colombiano?

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    Dry forests represent almost half of the world’s tropical forests and they are the most threatened ecosystems by human activities. The growing a knowledge in preservation of the few remaining underlines the significance of establishing monitoring strategies for dry forests which would illustrate their role in the context of the tropical forests’ preservation. In 2001, we began to establish permanent monitoring parcels in the Caribe dry forest. Today, with the support of both, national and international institutions and local actors, a network of 11 widely spread across the region parcels has been established to cover the most important remnants of dry forest from the Caribbean coast, accounting all climatic gradients present. The results obtained by the network include: contents of carbon and forest diversity in relation with climatic variables, carbon fixation rates and population dynamics of important species for the restoration. However, the lack of institutional support at regional and national levels, with some important exceptions, puts at risk the continuity of this important project for the dry forest preservation in context of climatic change adaptation. Nowadays, other institutions have replied to this initiative and have made advances on their own, establishing new monitoring sites in the Caribbean forests. It is of high priority to work for the integration of these efforts in order to create a more ambitious strategy for monitoring the Caribbean forests. For this, interest and compromise from regional institutions and researchers are requiredLos ecosistemas secos ocupan casi la mitad del área total de franja tropical y están entre los más amenazados por las actividades humanas a escala global. El reconocimiento creciente de la importancia de conservar los pocos remanentes que quedan y de iniciar actividades de restauración, resalta la importancia de establecer programas de monitoreo del bosque seco. En 2001 se inició el establecimiento de parcelas permanentes de monitoreo del bosque seco Caribe, con el apoyo de instituciones nacionales e internacionales; a la fecha existen 11 ampliamente distribuidas en algunos de los remanentes de bosque seco más importantesnde la costa Caribe. Los resultados provenientes de la red incluyen el contenido de carbono y la diversidad del bosque en relaciónncon variables climáticas, tasas de fijación de carbono y dinámica de poblaciones de especies importantes para la restauración. No obstante, la falta de apoyo institucional a nivel nacional y regional, con algunas excepciones importantes, pone en peligro la continuidad de este proyecto de alta importancia para la conservación del bosque seco en el contexto de la adaptación al cambio climático. Actualmente, otras instituciones han replicado esta iniciativa y avanzado aisladamente en el establecimiento de nuevos sitios de monitoreo de los bosques del Caribe. Es altamente prioritario trabajar por la integración de estos esfuerzos ya que pueden ser la base para un programa de monitoreo más ambicioso de los bosques del Caribe. Para ello se requiere el interés y el compromiso de instituciones e investigadores de la región Caribe.

    Updated European Heart Rhythm Association practical guide on the use of non-vitamin-K antagonist anticoagulants in patients with non-valvular atrial fibrillation: Executive summary

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    In 2013, the European Heart Rhythm Association (EHRA) published a Practical Guide on the use of non-VKA oral anticoagulants (NOACs) in patients with atrial fibrillation (AF) (Heidbuchel H, Verhamme P, Alings M, Antz M, Hacke W, Oldgren J, Sinnaeve P, Camm AJ, Kirchhof P, European Heart Rhythm A. European Heart Rhythm Association Practical Guide on the use of new oral anticoagulants in patients with non-valvular atrial fibrillation. Europace 2013;15:625-651; Heidbuchel H, Verhamme P, Alings M, Antz M, Hacke W, Oldgren J, Sinnaeve P, Camm AJ, Kirchhof P. EHRA practical guide on the use of new oral anticoagulants in patients with non-valvular atrial fibrillation: executive summary. Eur Heart J 2013;34:2094-2106). The document received widespread interest, not only from cardiologists but also from neurologists, geriatricians, and general practitioners, as became evident from the distribution of > 350 000 copies of its pocket version (the EHRA Key Message Booklet) world-wide. Since 2013, numerous new studies have appeared on different aspects of NOAC therapy in AF patients. Therefore, EHRA updated the Practical Guide, including new information but also providing balanced guiding in the many areas where prospective data are still lacking. The outline of the original guide that addressed 15 clinical scenarios has been preserved, but all chapters have been rewritten. Main changes in the Update comprise a discussion on the definition of 'non-valvular AF' and eligibility for NOAC therapy, inclusion of finalized information on the recently approved edoxaban, tailored dosing information dependent on concomitant drugs, and/or clinical characteristics, an expanded chapter on neurologic scenarios (ischaemic stroke or intracranial haemorrhage under NOAC), an updated anticoagulation card and more specifics on start-up and follow-up issues. There are also many new flow charts, like on appropriate switching between anticoagulants (VKA to NOAC or vice versa), default scenarios for acute management of coronary interventions, step-down schemes for longterm combined antiplatelet-anticoagulant management in coronary heart disease, management of bleeding, and cardioversion under NOAC therapy. The Updated Guide is available in full in EP Europace (Heidbuchel H, Verhamme P, Alings M, Antz M, Diener HC, HackeW, Oldgren J, Sinnaeve P, Camm AJ, Kirchhof P, Advisors. Updated European Heart Rhythm Association Practical Guide on the use of non-vitamin K antagonist anticoagulants in patients with non-valvular atrial fibrillation. Europace 2015;17:1467-1507), while additional resources can be found at the related ESC/EHRA website (www.NOACforAF.eu)

    High-resolution CT phenotypes in pulmonary sarcoidosis: a multinational Delphi consensus study

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    One view of sarcoidosis is that the term covers many different diseases. However, no classification framework exists for the future exploration of pathogenetic pathways, genetic or trigger predilections, patterns of lung function impairment, or treatment separations, or for the development of diagnostic algorithms or relevant outcome measures. We aimed to establish agreement on high-resolution CT (HRCT) phenotypic separations in sarcoidosis to anchor future CT research through a multinational two-round Delphi consensus process. Delphi participants included members of the Fleischner Society and the World Association of Sarcoidosis and other Granulomatous Disorders, as well as members' nominees. 146 individuals (98 chest physicians, 48 thoracic radiologists) from 28 countries took part, 144 of whom completed both Delphi rounds. After rating of 35 Delphi statements on a five-point Likert scale, consensus was achieved for 22 (63%) statements. There was 97% agreement on the existence of distinct HRCT phenotypes, with seven HRCT phenotypes that were categorised by participants as non-fibrotic or likely to be fibrotic. The international consensus reached in this Delphi exercise justifies the formulation of a CT classification as a basis for the possible definition of separate diseases. Further refinement of phenotypes with rapidly achievable CT studies is now needed to underpin the development of a formal classification of sarcoidosis

    Metal-Substituted Microporous Aluminophosphates

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    This chapter aims to present the zeotypes aluminophosphates (AlPOs) as a complementary alternative to zeolites in the isomorphic incorporation of metal ions within all-inorganic microporous frameworks as well as to discuss didactically the catalytic consequences derived from the distinctive features of both frameworks. It does not intend to be a compilation of either all or the most significant publications involving metal-substituted microporous aluminophosphates. Families of AlPOs and zeolites, which include metal ion-substituted variants, are the dominant microporous materials. Both these systems are widely used as catalysts, in particular through aliovalent metal ions substitution. Here, some general description of the synthesis procedures and characterization techniques of the MeAPOs (metal-contained aluminophosphates) is given along with catalytic properties. Next, some illustrative examples of the catalytic possibilities of MeAPOs as catalysts in the transformation of the organic molecules are given. The oxidation of the hardly activated hydrocarbons has probably been the most successful use of AlPOs doped with the divalent transition metal ions Co2+, Mn2+, and Fe2+, whose incorporation in zeolites is disfavoured. The catalytic role of these MeAPOs is rationalized based on the knowledge acquired from a combination of the most advanced characterization techniques. Finally, the importance of the high specificity of the structure-directing agents employed in the preparation of MeAPOs is discussed taking N,N-methyldicyclohexylamine in the synthesis of AFI-structured materials as a driving force. It is shown how such a high specificity could be predicted and how it can open great possibilities in the control of parameters as critical in catalysis as crystal size, inter-and intracrystalline mesoporosity, acidity, redox properties, incorporation of a great variety of heteroatom ions or final environment of the metal site (surrounding it by either P or Al)

    Genetic mechanisms of critical illness in COVID-19.

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    Host-mediated lung inflammation is present1, and drives mortality2, in the critical illness caused by coronavirus disease 2019 (COVID-19). Host genetic variants associated with critical illness may identify mechanistic targets for therapeutic development3. Here we report the results of the GenOMICC (Genetics Of Mortality In Critical Care) genome-wide association study in 2,244 critically ill patients with COVID-19 from 208 UK intensive care units. We have identified and replicated the following new genome-wide significant associations: on chromosome 12q24.13 (rs10735079, P = 1.65 × 10-8) in a gene cluster that encodes antiviral restriction enzyme activators (OAS1, OAS2 and OAS3); on chromosome 19p13.2 (rs74956615, P = 2.3 × 10-8) near the gene that encodes tyrosine kinase 2 (TYK2); on chromosome 19p13.3 (rs2109069, P = 3.98 ×  10-12) within the gene that encodes dipeptidyl peptidase 9 (DPP9); and on chromosome 21q22.1 (rs2236757, P = 4.99 × 10-8) in the interferon receptor gene IFNAR2. We identified potential targets for repurposing of licensed medications: using Mendelian randomization, we found evidence that low expression of IFNAR2, or high expression of TYK2, are associated with life-threatening disease; and transcriptome-wide association in lung tissue revealed that high expression of the monocyte-macrophage chemotactic receptor CCR2 is associated with severe COVID-19. Our results identify robust genetic signals relating to key host antiviral defence mechanisms and mediators of inflammatory organ damage in COVID-19. Both mechanisms may be amenable to targeted treatment with existing drugs. However, large-scale randomized clinical trials will be essential before any change to clinical practice

    Whole-genome sequencing reveals host factors underlying critical COVID-19

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    Critical COVID-19 is caused by immune-mediated inflammatory lung injury. Host genetic variation influences the development of illness requiring critical care1 or hospitalization2–4 after infection with SARS-CoV-2. The GenOMICC (Genetics of Mortality in Critical Care) study enables the comparison of genomes from individuals who are critically ill with those of population controls to find underlying disease mechanisms. Here we use whole-genome sequencing in 7,491 critically ill individuals compared with 48,400 controls to discover and replicate 23 independent variants that significantly predispose to critical COVID-19. We identify 16 new independent associations, including variants within genes that are involved in interferon signalling (IL10RB and PLSCR1), leucocyte differentiation (BCL11A) and blood-type antigen secretor status (FUT2). Using transcriptome-wide association and colocalization to infer the effect of gene expression on disease severity, we find evidence that implicates multiple genes—including reduced expression of a membrane flippase (ATP11A), and increased expression of a mucin (MUC1)—in critical disease. Mendelian randomization provides evidence in support of causal roles for myeloid cell adhesion molecules (SELE, ICAM5 and CD209) and the coagulation factor F8, all of which are potentially druggable targets. Our results are broadly consistent with a multi-component model of COVID-19 pathophysiology, in which at least two distinct mechanisms can predispose to life-threatening disease: failure to control viral replication; or an enhanced tendency towards pulmonary inflammation and intravascular coagulation. We show that comparison between cases of critical illness and population controls is highly efficient for the detection of therapeutically relevant mechanisms of disease

    Whole-genome sequencing reveals host factors underlying critical COVID-19

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    Critical COVID-19 is caused by immune-mediated inflammatory lung injury. Host genetic variation influences the development of illness requiring critical care1 or hospitalization2,3,4 after infection with SARS-CoV-2. The GenOMICC (Genetics of Mortality in Critical Care) study enables the comparison of genomes from individuals who are critically ill with those of population controls to find underlying disease mechanisms. Here we use whole-genome sequencing in 7,491 critically ill individuals compared with 48,400 controls to discover and replicate 23 independent variants that significantly predispose to critical COVID-19. We identify 16 new independent associations, including variants within genes that are involved in interferon signalling (IL10RB and PLSCR1), leucocyte differentiation (BCL11A) and blood-type antigen secretor status (FUT2). Using transcriptome-wide association and colocalization to infer the effect of gene expression on disease severity, we find evidence that implicates multiple genes—including reduced expression of a membrane flippase (ATP11A), and increased expression of a mucin (MUC1)—in critical disease. Mendelian randomization provides evidence in support of causal roles for myeloid cell adhesion molecules (SELE, ICAM5 and CD209) and the coagulation factor F8, all of which are potentially druggable targets. Our results are broadly consistent with a multi-component model of COVID-19 pathophysiology, in which at least two distinct mechanisms can predispose to life-threatening disease: failure to control viral replication; or an enhanced tendency towards pulmonary inflammation and intravascular coagulation. We show that comparison between cases of critical illness and population controls is highly efficient for the detection of therapeutically relevant mechanisms of disease
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