Centerline Depletion in Direct-Chill Cast Aluminum Alloys: The Avalanche Effect and Its Consequence for Turbulent Jet Casting

Avalanche dynamics of sedimenting grains in direct-chill casting of aluminum ingots is investigated as a primary driving force for centerline segregation. An analytical model predicting the importance of avalanche events as a function of casting parameters is proposed and validated with prior art results. New experimental results investigating the transient and steady-state centerline segregation of DC casting with a turbulent jet are reported

Continuous Casting of Multi-Alloy Metal Products and Related Methods

Described are multi-alloy metal products formed by a continuous casting system, as well as methods of continuously casting multi-alloy metal products. The disclosed multi-alloy metal product includes a plurality of layers of metallurgically bonded together metal alloys. The layers can be distributed along the thickness of the metal product or along the width of the metal product. The disclosed continuous casting system includes a plurality of injectors configured to simultaneously inject a plurality of metal alloys into a casting cavity to form the multi-alloy metal product

Predicting severe pain after major surgery: a secondary analysis of the Peri-operative Quality Improvement Programme (PQIP) dataset

Acute postoperative pain is common, distressing and associated with increased morbidity. Targeted interventions can prevent its development. We aimed to develop and internally validate a predictive tool to pre-emptively identify patients at risk of severe pain following major surgery. We analysed data from the UK Peri-operative Quality Improvement Programme to develop and validate a logistic regression model to predict severe pain on the first postoperative day using pre-operative variables. Secondary analyses included the use of peri-operative variables. Data from 17,079 patients undergoing major surgery were included. Severe pain was reported by 3140 (18.4%) patients; this was more prevalent in females, patients with cancer or insulin-dependent diabetes, current smokers and in those taking baseline opioids. Our final model included 25 pre-operative predictors with an optimism-corrected c-statistic of 0.66 and good calibration (mean absolute error 0.005, p = 0.35). Decision-curve analysis suggested an optimal cut-off value of 20–30% predicted risk to identify high-risk individuals. Potentially modifiable risk factors included smoking status and patient-reported measures of psychological well-being. Non-modifiable factors included demographic and surgical factors. Discrimination was improved by the addition of intra-operative variables (likelihood ratio χ2 496.5, p < 0.001) but not by the addition of baseline opioid data. On internal validation, our pre-operative prediction model was well calibrated but discrimination was moderate. Performance was improved with the inclusion of peri-operative covariates suggesting pre-operative variables alone are not sufficient to adequately predict postoperative pain

Measuring universal health coverage based on an index of effective coverage of health services in 204 countries and territories, 1990–2019: a systematic analysis for the Global Burden of Disease Study 2019

Background Achieving universal health coverage (UHC) involves all people receiving the health services they need, of high quality, without experiencing financial hardship. Making progress towards UHC is a policy priority for both countries and global institutions, as highlighted by the agenda of the UN Sustainable Development Goals (SDGs) and WHO's Thirteenth General Programme of Work (GPW13). Measuring effective coverage at the health-system level is important for understanding whether health services are aligned with countries' health profiles and are of sufficient quality to produce health gains for populations of all ages. Methods Based on the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019, we assessed UHC effective coverage for 204 countries and territories from 1990 to 2019. Drawing from a measurement framework developed through WHO's GPW13 consultation, we mapped 23 effective coverage indicators to a matrix representing health service types (eg, promotion, prevention, and treatment) and five population-age groups spanning from reproductive and newborn to older adults (≥65 years). Effective coverage indicators were based on intervention coverage or outcome-based measures such as mortality-to-incidence ratios to approximate access to quality care; outcome-based measures were transformed to values on a scale of 0–100 based on the 2·5th and 97·5th percentile of location-year values. We constructed the UHC effective coverage index by weighting each effective coverage indicator relative to its associated potential health gains, as measured by disability-adjusted life-years for each location-year and population-age group. For three tests of validity (content, known-groups, and convergent), UHC effective coverage index performance was generally better than that of other UHC service coverage indices from WHO (ie, the current metric for SDG indicator 3.8.1 on UHC service coverage), the World Bank, and GBD 2017. We quantified frontiers of UHC effective coverage performance on the basis of pooled health spending per capita, representing UHC effective coverage index levels achieved in 2019 relative to country-level government health spending, prepaid private expenditures, and development assistance for health. To assess current trajectories towards the GPW13 UHC billion target—1 billion more people benefiting from UHC by 2023—we estimated additional population equivalents with UHC effective coverage from 2018 to 2023. Findings Globally, performance on the UHC effective coverage index improved from 45·8 (95% uncertainty interval 44·2–47·5) in 1990 to 60·3 (58·7–61·9) in 2019, yet country-level UHC effective coverage in 2019 still spanned from 95 or higher in Japan and Iceland to lower than 25 in Somalia and the Central African Republic. Since 2010, sub-Saharan Africa showed accelerated gains on the UHC effective coverage index (at an average increase of 2·6% [1·9–3·3] per year up to 2019); by contrast, most other GBD super-regions had slowed rates of progress in 2010–2019 relative to 1990–2010. Many countries showed lagging performance on effective coverage indicators for non-communicable diseases relative to those for communicable diseases and maternal and child health, despite non-communicable diseases accounting for a greater proportion of potential health gains in 2019, suggesting that many health systems are not keeping pace with the rising non-communicable disease burden and associated population health needs. In 2019, the UHC effective coverage index was associated with pooled health spending per capita (r=0·79), although countries across the development spectrum had much lower UHC effective coverage than is potentially achievable relative to their health spending. Under maximum efficiency of translating health spending into UHC effective coverage performance, countries would need to reach $1398 pooled health spending per capita (US$ adjusted for purchasing power parity) in order to achieve 80 on the UHC effective coverage index. From 2018 to 2023, an estimated 388·9 million (358·6–421·3) more population equivalents would have UHC effective coverage, falling well short of the GPW13 target of 1 billion more people benefiting from UHC during this time. Current projections point to an estimated 3·1 billion (3·0–3·2) population equivalents still lacking UHC effective coverage in 2023, with nearly a third (968·1 million [903·5–1040·3]) residing in south Asia. Interpretation The present study demonstrates the utility of measuring effective coverage and its role in supporting improved health outcomes for all people—the ultimate goal of UHC and its achievement. Global ambitions to accelerate progress on UHC service coverage are increasingly unlikely unless concerted action on non-communicable diseases occurs and countries can better translate health spending into improved performance. Focusing on effective coverage and accounting for the world's evolving health needs lays the groundwork for better understanding how close—or how far—all populations are in benefiting from UHC

Experimental observations and analysis of macrosegregation in rolling slab ingots

Thesis: S.M., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2015.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student-submitted PDF version of thesis.Includes bibliographical references (pages 45-47).The increased demand for aluminum as a primary structural metal stems from a quest in automotive, aerospace, and marine industries to be more energy efficient and sustainable. This unprecedented demand drives aluminum casting methods towards increased productivity looking to, cast larger ingots faster. The unfortunate consequence of this approach is an enhanced variation of metallurgical properties over the cross section of slab ingots. Rolling slab ingots of AlCu4.5 using a typical Direct-Chill casting technique have been cast and sectioned for analysis. This alloy allowed us to compare our results with the available literature and to elucidate the marked differences in spatial variation of microstructure and composition found in radial and lateral symmetry castings. In an attempt to couple conventional theory with our results, sump and temperature profiles were measured in-situ and modeled using a commercial finite element analysis software package. The combination of experimental and modeling results indicate that the variations in the cooling parameters through the cross section are largely responsible for the spatial variances in metallurgical properties, pointing to a possible refinement of DC casting parameters.by Samuel R. Wagstaff.S.M

Влияние рециклинга на механические свойства алюминиевых сплавов серии 6ХХХ

Increasing the recycle content of a production stream is one of the easiest methods to reduce the cost of wrought aluminum products. This has economic and environmental benefits, but closed loop recycling systems do not reflect the conservation of the original composition, due to so called “tramp elements”. To understand the influence of certain tramp elements, a campaign of 950 AA6008 ingots were cast reflecting the entire scope of the composition window for this alloy, and the mechanical properties subsequently analyzedПовышение доли содержания вторичного металла в производственной цепочке является одним из самых простых способов снижения стоимости продукции из деформируемых алюминиевых сплавов. Это имеет экономические и экологические преимущества, но системы рециклинга замкнутого контура не отражают сохранение исходного состава из-за так называемых остаточных элементов. Чтобы понять влияние конкретных остаточных элементов, было произведено 950 слитков из сплава AA6008, отразивших весь диапазон состава этого сплава, и затем проанализированы механические свойств

Влияние рециклинга на механические свойства алюминиевых сплавов серии 6ХХХ

Increasing the recycle content of a production stream is one of the easiest methods to reduce the cost of wrought aluminum products. This has economic and environmental benefits, but closed loop recycling systems do not reflect the conservation of the original composition, due to so called “tramp elements”. To understand the influence of certain tramp elements, a campaign of 950 AA6008 ingots were cast reflecting the entire scope of the composition window for this alloy, and the mechanical properties subsequently analyzedПовышение доли содержания вторичного металла в производственной цепочке является одним из самых простых способов снижения стоимости продукции из деформируемых алюминиевых сплавов. Это имеет экономические и экологические преимущества, но системы рециклинга замкнутого контура не отражают сохранение исходного состава из-за так называемых остаточных элементов. Чтобы понять влияние конкретных остаточных элементов, было произведено 950 слитков из сплава AA6008, отразивших весь диапазон состава этого сплава, и затем проанализированы механические свойств

Dynamic Cryptographic Hash Functions

Abstract. We present the dynamic cryptographic hash function, a new type of hash function which takes two parameters instead of one. The additional parameter, the security parameter, specifies the internal workings and size of the digest produced. We provide a formal definitions for a dynamic cryptographic hash function and for the traditional security properties, modified for dynamic hash functions. Two additional properties, security parameter collision resistance and digest resistance, are also defined. The additional properties are motivated by scenarios where a dynamic hash functions more cleanly provides a solution to a typical cryptographic problem

Thigh-length compression stockings and DVT after stroke

Controversy exists as to whether neoadjuvant chemotherapy improves survival in patients with invasive bladder cancer, despite randomised controlled trials of more than 3000 patients. We undertook a systematic review and meta-analysis to assess the effect of such treatment on survival in patients with this disease