Spark plasma sintering of alumina: Study of parameters, formal sintering analysis and hypotheses on the mechanism(s) involved in densification and grain growth

The spark plasma sintering (SPS) of an undoped commercial α-Al2O3 powder (0.14 μm) was investigated. The SPS parameters such as the dwell temperature, applied external pressure, temperature of pressure application, dwell time and pulse pattern were varied. A sintering path (relative density vs. grain size) showing two regimes has been brought to the fore: densification without grain growth occurring at the lower temperatures and grain growth without much further densification taking place at the higher temperatures, with a threshold between 1100 and 1200 °C. In addition, a formal sintering analysis was performed in order to identify the mechanism(s) involved in densification and grain growth

Comparison of Filtering Methods for the Modeling and Retrospective Forecasting of Influenza Epidemics

A variety of filtering methods enable the recursive estimation of system state variables and inference of model parameters. These methods have found application in a range of disciplines and settings, including engineering design and forecasting, and, over the last two decades, have been applied to infectious disease epidemiology. For any system of interest, the ideal filter depends on the nonlinearity and complexity of the model to which it is applied, the quality and abundance of observations being entrained, and the ultimate application (e.g. forecast, parameter estimation, etc.). Here, we compare the performance of six state-of-the-art filter methods when used to model and forecast influenza activity. Three particle filters—a basic particle filter (PF) with resampling and regularization, maximum likelihood estimation via iterated filtering (MIF), and particle Markov chain Monte Carlo (pMCMC)—and three ensemble filters—the ensemble Kalman filter (EnKF), the ensemble adjustment Kalman filter (EAKF), and the rank histogram filter (RHF)—were used in conjunction with a humidity-forced susceptible-infectious-recovered-susceptible (SIRS) model and weekly estimates of influenza incidence. The modeling frameworks, first validated with synthetic influenza epidemic data, were then applied to fit and retrospectively forecast the historical incidence time series of seven influenza epidemics during 2003–2012, for 115 cities in the United States. Results suggest that when using the SIRS model the ensemble filters and the basic PF are more capable of faithfully recreating historical influenza incidence time series, while the MIF and pMCMC do not perform as well for multimodal outbreaks. For forecast of the week with the highest influenza activity, the accuracies of the six model-filter frameworks are comparable; the three particle filters perform slightly better predicting peaks 1–5 weeks in the future; the ensemble filters are more accurate predicting peaks in the past

Folic acid source, usual intake, and folate and vitamin B-12 status in US adults: National Health and Nutrition Examination Survey (NHANES) 2003–2006

Background: US adults have access to multiple sources of folic acid. The contribution of these sources to usual intakes above the tolerable upper intake level (UL) (1000 ug/d) and to folate and vitamin B-12 status is unknown. Objective: The objective was to estimate usual folic acid intake above the UL and adjusted serum and red blood cell folate, vitamin B-12, methylmalonic acid, and homocysteine concentrations among US adults by 3 major folic acid intake sources - enriched cereal-grain products (ECGP), ready-to-eat cereals (RTE), and supplements (SUP) - categorized into 4 mutually exclusive consumption groups. Design: We used data from the National Health and Nutrition Examination Survey (NHANES) 2003-2006 (n = 8258). Results: Overall, 2.7% (95% CI: 1.9%, 3.5%) of adults consumed more than the UL of folic acid. The proportions of those who consumed folic acid from ECGP only, ECGP+RTE, ECGP+SUP, and ECGP+RTE+SUP were 42%, 18%, 25%, and 15%, respectively. Of 60% of adults who did not consume supplements containing folic acid (ECGP only and ECGP+RTE), 0% had intakes that exceeded the UL. Of 34% and 6% of adults who consumed supplements with an average of \u3c400 and \u3e400 ug folic acid/d, \u3c1% and 47.8% (95% CI: 39.6%, 56.0%), respectively, had intakes that exceeded the UL. Consumption of RTE and/or supplements with folic acid was associated with higher folate and vitamin B-12 and lower homocysteine concentrations, and consumption of supplements with vitamin B-12 was associated with lower methylmalonic acid concentrations (P \u3c 0.001). Conclusion: At current fortification levels, US adults who do not consume supplements or who consume an average of \u3c400 ug folic acid/d from supplements are unlikely to exceed the UL in intake for folic acid

Exploring factors influencing pre-service and in-service teachers´ perception of digital competencies in the Chinese region of Anhui

[EN] The emergence of the Covid-19 pandemic has accelerated the wave of digital social transformation worldwide and pushed the “Accelerator Key” for the digital trans formation of education in 2020. This transformation has also impacted in an all around way in China. Taking Anhui province as a case study, this research explores socio-demographic factors infuencing the digital competence level of pre- and in service teachers of primary and secondary education in China. The quantitative methodological approach emphasizes the study subjects’ perception of their digital competencies in three factors: basic technology literacy, technical support learning, and technical support teaching. The study involved 250 pre-service teachers and 248 in-service teachers. The main fndings are: (1) participants have good consciousness and attitudes towards using ICT in daily work, but their educational practice is weak; (2) in-service teachers have a digital competence level generally higher than pre-service teachers’, which might be their professional practice promote them to refect on perceptions and attitudes regarding technological education; (3) for in service teachers, there are signifcant diferences between their digital competence level and age, years of teaching experience, educational background; (4) current ICT courses have no infuencing on in-service teachers’ digital competence level, implying that current ICT training system may have problems. The study provides insights to improve pre-service teachers’ digital competence education in universi ties and develop well-designed in-service teachers’ ICT training courses.Publicación en abierto financiada por el Consorcio de Bibliotecas Universitarias de Castilla y León (BUCLE), con cargo al Programa Operativo 2014ES16RFOP009 FEDER 2014-2020 DE CASTILLA Y LEÓN, Actuación:20007-CL - Apoyo Consorcio BUCLE

Real-Time Influenza Forecasts during the 2012–2013 Season

Recently, we developed a seasonal influenza prediction system that uses an advanced data assimilation technique and real-time estimates of influenza incidence to optimize and initialize a population-based mathematical model of influenza transmission dynamics. This system was used to generate and evaluate retrospective forecasts of influenza peak timing in New York City. Here we present weekly forecasts of seasonal influenza developed and run in real time for 108 cites in the United States during the recent 2012–2013 season. Reliable ensemble forecasts of influenza outbreak peak timing with leads of up to 9 weeks were produced. Forecast accuracy increased as the season progressed, and the forecasts significantly outperformed alternate, analog prediction methods. By Week 52, prior to peak for the majority of cities, 63% of all ensemble forecasts were accurate. To our knowledge, this is the first time predictions of seasonal influenza have been made in real time and with demonstrated accuracy

Control of scar tissue formation in the cornea: strategies in clinical and corneal tissue engineering

Corneal structure is highly organized and unified in architecture with structural and functional integration which mediates transparency and vision. Disease and injury are the second most common cause of blindness affecting over 10 million people worldwide. Ninety percent of blindness is permanent due to scarring and vascularization. Scarring caused via fibrotic cellular responses, heals the tissue, but fails to restore transparency. Controlling keratocyte activation and differentiation are key for the inhibition and prevention of fibrosis. Ophthalmic surgery techniques are continually developing to preserve and restore vision but corneal regression and scarring are often detrimental side effects and long term continuous follow up studies are lacking or discouraging. Appropriate corneal models may lead to a reduced need for corneal transplantation as presently there are insufficient numbers or suitable tissue to meet demand. Synthetic optical materials are under development for keratoprothesis although clinical use is limited due to implantation complications and high rejection rates. Tissue engineered corneas offer an alternative which more closely mimic the morphological, physiological and biomechanical properties of native corneas. However, replication of the native collagen fiber organization and retaining the phenotype of stromal cells which prevent scar-like tissue formation remains a challenge. Careful manipulation of culture environments are under investigation to determine a suitable environment that simulates native ECM organization and stimulates keratocyte migration and generation

Fabrication and Characterisation of Hydrogels with Reversible Wrinkled Surfaces for Limbal Study and Reconstruction

In the biomedical field, there is a demand for the development of novel approaches for the investigation of optical epithelial anatomical features with biomimetic materials. These materials are not only required to replicate structures but also enable dynamic modelling for disease states such as limbal stem cell deficiency and ageing. In the present study, the effective generation of reversible wrinkled polydimethylsiloxane (PDMS) substrates was undertaken to mimic the undulating anatomy of the limbal epithelial stem cell niche. This undulating surface pattern was formed through a dual treatment with acid oxidation and plasma using an innovatively designed stretching frame. This system enabled the PDMS substrate to undergo deformation and relaxation, creating a reversible and tuneable wrinkle pattern with cell culture applications. The crypt-like pattern exhibited a width of 70–130 µm and a depth of 17–40 µm, resembling the topography of a limbal epithelial stem cell niche, which is characterised by an undulating anatomy. The cytocompatibility of the patterned substrate was markedly improved using a gelatin methacrylate polymer (GelMa) coating. It was also observed that these wrinkled PDMS surfaces were able to dictate cell growth patterns, showing alignment in motile cells and colony segregation in colony-forming cells when using human and porcine limbal cells, respectively

COMIT: identification of noncoding motifs under selection in coding sequences

COMIT is presented; an algorithm for detecting functional non-coding motifs in coding regions, separating nucleotide and amino acid effects

Mechanical characterization of hydrogels and its implications for cellular activities

Mechanical characterization of hydrogels and its implications for cellular activitie