143 research outputs found

    Periodically modulated geometric and electronic structure of graphene on Ru(0001)

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    We report here on a method to fabricate and characterize highly perfect, periodically rippled graphene monolayers and islands, epitaxially grown on single crystal metallic substrates under controlled UHV conditions. The periodicity of the ripples is dictated by the difference in lattice parameters of graphene and substrate, and, thus, it is adjustable. We characterize its perfection at the atomic scale by means of STM and determine its electronic structure in the real space by local tunnelling spectroscopy. There are periodic variations in the geometric and electronic structure of the graphene monolayer. We observe inhomogeneities in the charge distribution, i.e a larger occupied Density Of States at the higher parts of the ripples. Periodically rippled graphene might represent the physical realization of an ordered array of coupled graphene quantum dots. The data show, however, that for rippled graphene on Ru(0001) both the low and the high parts of the ripples are metallic. The fabrication of periodically rippled graphene layers with controllable characteristic length and different bonding interactions with the substrate will allow a systematic experimental test of this fundamental problem.Comment: 12 pages. Contribution to the topical issue on graphene of Semiconductor Science and Technolog

    Estructuras y procesos espaciales del municipio de Montería en su contexto rural

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    Abstract This article shows part of the results of the research work called “Spatial and Functional Organization of the Rural Area of ​​the Municipality of Montería, Department of Córdoba, Colombia: Bases for the Planning of the Rural Space (Corregimental). In such a way, it aims to determine the spatial structures and processes that affect the configuration and spatial distribution of rural settlements. Theoretically and methodologically supported from the spatial approach in geography, through Location Theory and Graphs, through the deductive-analytical and explanatory method. The municipality of Montería in its rural context reflects strong spatial imbalances as a result of the high population, economic, administrative and political concentration around the municipal seat, generating a low level of development in the rest of the rural settlements distributed in a dispersed manner, with population sizes very small and isolated over a large area of ​​territory, limited mainly by spatial structures of location and the distance between rural settlements, caused mainly by physical, historical, economic, social and political elements that reveal the lack of territorial cohesion of the rural space in the municipality of Montería.Resumen Este artículo muestra parte de los resultados del trabajo de investigación denominado “Organización Espacial y Funcional del Área Rural del Municipio de Montería, Departamento De Córdoba, Colombia: Bases para la Planificación del Espacio Rural (Corregimental)”. El objetivo es determinar las estructuras y procesos espaciales que inciden en la configuración y distribución espacial de los asentamientos rurales. Se sustenta teórica y metodológicamente desde el enfoque espacial en geografía, mediante la teoría Locacional y de los Grafos, por medio del método deductivo – analítico y de tipo explicativo. El municipio de Montería en su contexto rural refleja fuertes desequilibrios espaciales producto de la alta concentración poblacional, económica, administrativa y política alrededor de la cabecera municipal, generando un bajo nivel de desarrollo en el resto de asentamientos rurales distribuidos de manera dispersa, con tamaños poblacionales muy reducidos y aislados en una gran extensión de territorio, limitados principalmente por estructuras espaciales de localización y la distancia entre asentamientos rurales, ocasionado principalmente por elementos físicos, históricos, económicos sociales y políticos que dejan en evidencia la falta de cohesión territorial del espacio rural en el  municipio de Montería

    Development of a monitoring system for COVID-19 monitoring in early stages

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    Covid-19 is considered the most infectious virus today. Likewise, the struggle to mitigate the effects of the variants, the flexibility in some measures such as the use of face masks, the advancement of vaccination and prevention and self-care campaigns continue to be topics of research and of global interest. The world health authorities published that the disease was characterized by presenting the same symptoms as the flu along with a complex picture where in the most serious cases they lead to difficulty breathing due to pneumonia, sepsis and septic shock that can lead to death. Some systems implemented for taking body temperature such as thermographic cameras, digital thermometers, for the description of symptoms in the people they analyze at the time of carrying out the epidemiological fences are not enough, since they handle low precision, are taken in isolation, individually or randomly and is not suitable for characterizing interest groups. Then, establishing risk levels by measuring non-invasive variables can be considered inputs into prevention campaigns and a low-cost way of monitoring the community. This article shows the design of a non-invasive embedded device for the measurement of 5 priority variables for the detection of the risk of covid-19 infection. The proposed device was duly calibrated and synchronized for the acquisition of data from 594 people in the city of Bucaramanga, Colombia, who authorize the monitoring of the symptoms. The people must be in a state of rest to be able to acquire the data with great accuracy, in this way the data is entered into the system in charge of doing the monitoring analysis. Additionally, the implementation of an interface that allows the visualization of results, laying the foundations for the development of automatic learning techniques or models for the risk classification in future work

    Study of Microscopic Residual Stresses in an Extruded Aluminium Alloy Sample after Thermal Treatment

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    Abstract: A method is proposed to calculate the microscopic residual stresses in extruded cylindrical samples of non-ageing aluminium alloy 5083 (Al–Mg), arising from quenching in fresh water from 530°C. We start from the premise that the alloy is single-phase and non-isotropic on a microscopic scale; it consists of many grains that exhibit different mechanical response depending on their crystallographic orientation and neighboring grains. Microscopic residual stresses depend on the applied heat treatment, microstructure and mechanical strength of the individual grains. The stresses were calculated from neutron diffraction data. Genetic programming algorithms were used to calculate microscopic residual stresses, considering that each diffraction peak describes the stress distribution of a group of grains having a certain orientation, size and environment. The algorithm assigns a stress value to each grain according to the distribution of the diffraction peaks and the microstructural parameters of these grains.This work was supported by the Madrid Regional Government-FEDER grant Y2018/NMT-4668 (Micro-Stress-MAP-CM) and the project MAT2017-83825-C4-1-R. We would also like to express our gratitude to FLNR-JINP for the beam time allocated on the FSD instrument, and to the HeuristicLab Software developers

    Heterologous expression screens in Nicotiana benthamiana identify a candidate effector of the wheat Yellow Rust Pathogen that associates with processing bodies

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    Rust fungal pathogens of wheat (Triticum spp.) affect crop yields worldwide. The molecular mechanisms underlying the virulence of these pathogens remain elusive, due to the limited availability of suitable molecular genetic research tools. Notably, the inability to perform high-throughput analyses of candidate virulence proteins (also known as effectors) impairs progress. We previously established a pipeline for the fast-forward screens of rust fungal candidate effectors in the model plant Nicotiana benthamiana. This pipeline involves selecting candidate effectors in silico and performing cell biology and protein-protein interaction assays in planta to gain insight into the putative functions of candidate effectors. In this study, we used this pipeline to identify and characterize sixteen candidate effectors from the wheat yellow rust fungal pathogen Puccinia striiformis f sp tritici. Nine candidate effectors targeted a specific plant subcellular compartment or protein complex, providing valuable information on their putative functions in plant cells. One candidate effector, PST02549, accumulated in processing bodies (P-bodies), protein complexes involved in mRNA decapping, degradation, and storage. PST02549 also associates with the P-body-resident ENHANCER OF mRNA DECAPPING PROTEIN 4 (EDC4) from N. benthamiana and wheat. We propose that P-bodies are a novel plant cell compartment targeted by pathogen effectors

    Sebacinales Everywhere: Previously Overlooked Ubiquitous Fungal Endophytes

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    Inconspicuous basidiomycetes from the order Sebacinales are known to be involved in a puzzling variety of mutualistic plant-fungal symbioses (mycorrhizae), which presumably involve transport of mineral nutrients. Recently a few members of this fungal order not fitting this definition and commonly referred to as ‘endophytes’ have raised considerable interest by their ability to enhance plant growth and to increase resistance of their host plants against abiotic stress factors and fungal pathogens. Using DNA-based detection and electron microscopy, we show that Sebacinales are not only extremely versatile in their mycorrhizal associations, but are also almost universally present as symptomless endophytes. They occurred in field specimens of bryophytes, pteridophytes and all families of herbaceous angiosperms we investigated, including liverworts, wheat, maize, and the non-mycorrhizal model plant Arabidopsis thaliana. They were present in all habitats we studied on four continents. We even detected these fungi in herbarium specimens originating from pioneering field trips to North Africa in the 1830s/40s. No geographical or host patterns were detected. Our data suggest that the multitude of mycorrhizal interactions in Sebacinales may have arisen from an ancestral endophytic habit by specialization. Considering their proven beneficial influence on plant growth and their ubiquity, endophytic Sebacinales may be a previously unrecognized universal hidden force in plant ecosystems

    The Chemokine CXCL12 Is Essential for the Clearance of the Filaria Litomosoides sigmodontis in Resistant Mice

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    Litomosoides sigmodontis is a cause of filarial infection in rodents. Once infective larvae overcome the skin barrier, they enter the lymphatic system and then settle in the pleural cavity, causing soft tissue infection. The outcome of infection depends on the parasite's modulatory ability and also on the immune response of the infected host, which is influenced by its genetic background. The goal of this study was to determine whether host factors such as the chemokine axis CXCL12/CXCR4, which notably participates in the control of immune surveillance, can influence the outcome of the infection. We therefore set up comparative analyses of subcutaneous infection by L. sigmodontis in two inbred mouse strains with different outcomes: one susceptible strain (BALB/c) and one resistant strain (C57BL/6). We showed that rapid parasite clearance was associated with a L. sigmodontis-specific CXCL12-dependent cell response in C57BL/6 mice. CXCL12 was produced mainly by pleural mesothelial cells during infection. Conversely, the delayed parasite clearance in BALB/c mice was neither associated with an increase in CXCL12 levels nor with cell influx into the pleural cavity. Remarkably, interfering with the CXCL12/CXCR4 axis in both strains of mice delayed filarial development, as evidenced by the postponement of the fourth molting process. Furthermore, the in vitro growth of stage 4 filariae was favored by the addition of low amounts of CXCL12. The CXCL12/CXCR4 axis thus appears to have a dual effect on the L. sigmodontis life cycle: by acting as a host-cell restriction factor for infection, and as a growth factor for worms

    Thalidomide plus dexamethasone as a maintenance therapy after autologous hematopoietic stem cell transplantation improves progression-free survival in multiple myeloma

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    Despite the good response of stem cell transplant (SCT) in the treatment of multiple myeloma (MM), most patients relapse or do not achieve complete remission, suggesting that additional treatment is needed. We assessed the impact of thalidomide in maintenance after SCT in untreated patients with MM. A hundred and eight patients (<70 years old) were randomized to receive maintenance with dexamethasone (arm A; n = 52) or dexamethasone with thalidomide (arm B; n = 56; 200 mg daily) for 12 months or until disease progression. After a median follow-up of 27 months, an intention to treat analysis showed a 2-year progression-free survival (PFS) of 30% in arm A (95% CI 2238) and 64% in arm B (95% CI 5771; P = 0.002), with median PFS of 19 months and 36 months, respectively. In patients who did not achieve at least a very good partial response, the PFS at 2 years was significantly higher when in use of thalidomide (19 vs. 59%; P = 0.002). Overall survival at 2 years was not significantly improved (70 vs. 85% in arm A and arm B, respectively; P = 0.27). The addition of thalidomide to dexamethasone as maintenance improved the PFS mainly in patients who did not respond to treatment after SCT. Am. J. Hematol. (c) 2012 Wiley Periodicals, Inc.FAPESP (Fundacao de Amparo a Pesquisa do Estado de Sao Paulo)Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)CNPq (Conselho Nacional do Desenvolvimento Cientifico e Tecnologico)Conselho Nacional do Desenvolvimento Cientifico e Tecnologico (CNPq)FAPERJ (Fundacao de Apoio a Pesquisa do Estado do Rio de Janeiro)FAPERJ (Fundacao de Apoio a Pesquisa do Estado do Rio de Janeiro

    Planck pre-launch status : The Planck mission

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    The comparative responsiveness of Hospital Universitario Princesa Index and other composite indices for assessing rheumatoid arthritis activity

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    Objective To evaluate the responsiveness in terms of correlation of the Hospital Universitario La Princesa Index (HUPI) comparatively to the traditional composite indices used to assess disease activity in rheumatoid arthritis (RA), and to compare the performance of HUPI-based response criteria with that of the EULAR response criteria. Methods Secondary data analysis from the following studies: ACT-RAY (clinical trial), PROAR (early RA cohort) and EMECAR (pre-biologic era long term RA cohort). Responsiveness was evaluated by: 1) comparing change from baseline (Delta) of HUPI with Delta in other scores by calculating correlation coefficients; 2) calculating standardised effect sizes. The accuracy of response by HUPI and by EULAR criteria was analyzed using linear regressions in which the dependent variable was change in global assessment by physician (Delta GDA-Phy). Results Delta HUPI correlation with change in all other indices ranged from 0.387 to 0.791); HUPI's standardized effect size was larger than those from the other indices in each database used. In ACT-RAY, depending on visit, between 65 and 80% of patients were equally classified by HUPI and EULAR response criteria. However, HUPI criteria were slightly more stringent, with higher percentage of patients classified as non-responder, especially at early visits. HUPI response criteria showed a slightly higher accuracy than EULAR response criteria when using Delta GDA-Phy as gold standard. Conclusion HUPI shows good responsiveness in terms of correlation in each studied scenario (clinical trial, early RA cohort, and established RA cohort). Response criteria by HUPI seem more stringent than EULAR''s
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