256 research outputs found

    DeepPrecip: A deep neural network for precipitation retrievals

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    Remotely-sensed precipitation retrievals are critical for advancing our understanding of global energy and hydrologic cycles in remote regions. Radar reflectivity profiles of the lower atmosphere are commonly linked to precipitation through empirical power laws, but these relationships are tightly coupled to particle microphysical assumptions that do not generalize well to different regional climates. Here, we develop a robust, highly generalized precipitation retrieval from a deep convolutional neural network (DeepPrecip) to estimate 20-minute average surface precipitation accumulation using near-surface radar data inputs. DeepPrecip displays high retrieval skill and can accurately model total precipitation accumulation, with a mean square error (MSE) 99 % lower, on average, than current methods. DeepPrecip also outperforms a less complex machine learning retrieval algorithm, demonstrating the value of deep learning when applied to precipitation retrievals. Predictor importance analyses suggest that a combination of both near-surface (below 1 km) and higher-altitude (1.5 &ndash; 2 km) radar measurements are the primary features contributing to retrieval accuracy. Further, DeepPrecip closely captures total precipitation accumulation magnitudes and variability across nine distinct locations without requiring any explicit descriptions of particle microphysics or geospatial covariates. This research reveals the important role for deep learning in extracting relevant information about precipitation from atmospheric radar retrievals.</p

    Steel corrosion in reinforced alkali-activated materials

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    The development of alkali-activated materials (AAMs) as an alternative to Portland cement (PC) has seen significant progress in the past decades. However, there still remains significant uncertainty regarding their long term performance when used in steel-reinforced structures. The durability of AAMs in such applications depends strongly on the corrosion behaviour of the embedded steel reinforcement, and the experimental data in the literature are limited and in some cases inconsistent. This letter elucidates the role of the chemistry of AAMs on the mechanisms governing passivation and chloride-induced corrosion of the steel reinforcement, to bring a better understanding of the durability of AAM structures exposed to chloride. The corrosion of the steel reinforcement in AAMs differs significantly from observations in PC; the onset of pitting (or the chloride ‘threshold’ value) depends strongly on the alkalinity, and the redox environment, of these binders. Classifications or standards used to assess the severity of steel corrosion in PC appear not to be directly applicable to AAMs due to important differences in pore solution chemistry and phase assemblage

    Steel reinforcement corrosion in alkali-activated fly ash mortars

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    Corrosion of steel rebars in concrete presents one of the main deterioration mechanisms limiting service life of the reinforced structures. The corrosion is accompanied by an expansion of the corrosion products causing high pressures, concrete cracking and finally spalling of a cover layer. Critical chloride concentration, loss of alkalinity and modeling of the steel corrosion are in researchers\u27 spotlight for decades, however reinforcement corrosion in alkali activated materials is insufficiently described and understood yet. In this work, the steel reinforcement corrosion in alkali-activated fly ash mortars is investigated in terms of electrochemical behaviour of the reinforced mortars exposed to aggressive environments such as leaching, carbonation and chloride ingress. A selected geopolymer mixture based on hard coal fly ash activated with sodium hydroxide and sodium silicate solutions is used for the steel reinforcement-corrosion experiments. The formation of passive layer on the steel rebars is observed after approx. two weeks of hardening at laboratory temperature. However, alternative heat-treatment at 80°C for several hours leads to immediate formation of the passive layer as well as to a faster strength gain (80 MPa after 24h at 80°C). Chloride-induced corrosion, leaching and carbonation resistance of the alkali activated fly ash-based concrete is studied, where leaching in deionized water or carbonation under natural conditions (~0.04 % CO2) for 300 days did not lead to corrosion of the embedded steel. On the other hand, accelerated carbonation under 100 % CO2 atmosphere lead to depassivation within two weeks. Please click Additional Files below to see the full abstract

    The importance of sex as a risk factor for hospital readmissions due to pulmonary diseases

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    BACKGROUND: Pulmonary diseases are a common and costly cause of 30-day readmissions. Few studies have focused on the difference in risk for rehospitalization between men and women in older patients. In this study we analyzed the association between sex and the risk of readmission in a cohort of patients admitted to the hospital for chronic obstructive pulmonary disease (COPD) exacerbation and other major pulmonary diseases. METHODS: This was a retrospective cohort study based on administrative data collected in the Veneto Region in 2016. We included 14,869 hospital admissions among residents aged 6565\u2009years for diagnosis related groups (DRGs) of the most common disorders of the respiratory system: bronchitis and asthma, pneumonia, pulmonary edema, respiratory failure, and COPD. Multilevel logistic regressions were performed to test the association between 30-day hospital readmission and sex, adjusting for confounding factors. RESULTS: For bronchitis and asthma, male patients had significantly higher odds of 30-day readmission than female patients (adjusted odds ratio (aOR), 2.07; 95% confidence interval (CI), 1.11-3.87). The odds of readmission for men were also significantly higher for pneumonia (aOR, 1.40; 95% CI, 1.13-1.72), for pulmonary edema and respiratory failure (aOR, 1.28; 95% CI, 1.05-1.55), and for COPD (aOR, 1.34; 95% CI, 1.00-1.81). CONCLUSIONS: This study found that male sex is a major risk factors for readmission in patients aged more than 65\u2009years with a primary pulmonary diagnosis. More studies are needed to understand the underlying determinants of this phenomena and to provide targets for future interventions

    Phenotype correction of fanconi anemia group a hematopoietic stem cells using lentiviral vector

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    AbstractFanconi anemia (FA) is an autosomal recessive disease characterized by progressive bone marrow failure due to defective stem cell function. FA patients' cells are hypersensitive to DNA cross-linking agents such as mitomycin C (MMC), exposure to which results in cytogenetic aberrations and cell death. To date Moloney murine leukemia virus vectors have been used in clinical gene therapy. Recently, third-generation lentiviral vectors based on the HIV-1 genome have been developed for efficient gene transfer to hematopoietic stem cells. We generated a self-inactivating lentiviral vector expressing the FA group A cDNA driven by the murine stem cell virus U3 LTR promoter and used the vector to transduce side-population (SP) cells isolated from bone marrow of Fanconi anemia group A (Fanca) knockout mice. One thousand transduced SP cells reconstituted the bone marrow of sublethally irradiated Fanca recipient mice. Phenotype correction was demonstrated by stable hematopoiesis following MMC challenge. Using real-time PCR, one proviral vector DNA copy per cell was detected in all lineage-committed cells in the peripheral blood of both primary and secondary recipients. Our results suggest that the lentiviral vector transduces stem cells capable of self-renewal and long-term hematopoiesis in vivo and is potentially useful for clinical gene therapy of FA hematopoietic cells

    Consensus of German Transplant Centers on Hematopoietic Stem Cell Transplantation in Fanconi Anemia

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    Allogeneic hematopoietic stem cell transplantation (HSCT) is currently the only curative therapy for the severe hematopoietic complications associated with Fanconi anemia (FA). In Germany, it is estimated that 10–15 transplants are performed annually for FA. However, because FA is a DNA repair disorder, standard conditioning regimens confer a high risk of excessive regimen-related toxicities and mortality, and reduced intensity regimens are linked with graft failure in some FA patients. Moreover, development of graft-versus-host disease is a major contributing factor for secondary solid tumors. The relative rarity of the disorder limits HSCT experience at any single center. Consensus meetings were convened to develop a national approach for HSCT in FA. This manuscript outlines current experience and knowledge about HSCT in FA and, based on this analysis, general recommendations reached at these meetings

    Screening for Impaired Visual Acuity in Older Adults: US Preventive Services Task Force Recommendation Statement

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    DESCRIPTION: Update of the US Preventive Services Task Force (USPSTF) recommendation on screening for impaired visual acuity in older adults. METHODS: The USPSTF reviewed the evidence on screening for visual acuity impairment associated with uncorrected refractive error, cataracts, and age-related macular degeneration among adults 65 years or older in the primary care setting; the benefits and harms of screening; the accuracy of screening; and the benefits and harms of treatment of early vision impairment due to uncorrected refractive error, cataracts, and age-related macular degeneration. POPULATION: This recommendation applies to asymptomatic adults 65 years or older who do not present to their primary care clinician with vision problems. RECOMMENDATION: The USPSTF concludes that the current evidence is insufficient to assess the balance of benefits and harms of screening for impaired visual acuity in older adults. (I statement)

    Improving the use of research evidence in guideline development: 9. Grading evidence and recommendations

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    BACKGROUND: The World Health Organization (WHO), like many other organisations around the world, has recognised the need to use more rigorous processes to ensure that health care recommendations are informed by the best available research evidence. This is the ninth of a series of 16 reviews that have been prepared as background for advice from the WHO Advisory Committee on Health Research to WHO on how to achieve this. OBJECTIVES: We reviewed the literature on grading evidence and recommendations in guidelines. METHODS: We searched PubMed and three databases of methodological studies for existing systematic reviews and relevant methodological research. We did not conduct a full systematic review ourselves. Our conclusions are based on the available evidence, consideration of what WHO and other organisations are doing and logical arguments. KEY QUESTIONS AND ANSWERS: Should WHO grade the quality of evidence and the strength of recommendations? • Users of recommendations need to know how much confidence they can place in the underlying evidence and the recommendations. The degree of confidence depends on a number of factors and requires complex judgments. These judgments should be made explicitly in WHO recommendations. A systematic and explicit approach to making judgments about the quality of evidence and the strength of recommendations can help to prevent errors, facilitate critical appraisal of these judgments, and can help to improve communication of this information. What criteria should be used to grade evidence and recommendations? • Both the quality of evidence and the strength of recommendations should be graded. The criteria used to grade the strength of recommendations should include the quality of the underlying evidence, but should not be limited to that. • The approach to grading should be one that has wide international support and is suitable for a wide range of different types of recommendations. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach, which is currently suggested in the Guidelines for WHO Guidelines, is being used by an increasing number of other organizations internationally. It should be used more consistently by WHO. Further developments of this approach should ensure its wide applicability. Should WHO use the same grading system for all of its recommendations? • Although there are arguments for and against using the same grading system across a wide range of different types of recommendations, WHO should use a uniform grading system to prevent confusion for developers and users of recommendations
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